Here is the most complete list of Twitter-mania that I've found.  I thought it might be useful for my fellow Active Rain friends who, like me, are just learning the ins and out to Twitter!!

Thank you to Lawrence Brand who posted this on his own Blog,http://twitter.com/mtgmantx

www.ifollowback.com You sign up on this website with the agreement that you will follow back at least 90% of those follow you.

www.tweetlater.com This is also another free service that allows you to automatically follow back those who follow you first. You can even send a direct message back to them automatically as well as several other features. There is a free and professional paid version.

HootSuite - You can manage multiple twitter accounts with this application. I have not personally used this one myself but plan to try it out. You can also schedule tweets, track clicks to your links (using HootSuite's ow.ly URL shortening service) and get an entire overview of each Twitter account with easy tab-based navigation.

TweetChannel - Confused by #hashtags in Twitter? You shouldn't be after reading this tutorial but if you'd like an easier way to send your tweets to a specific audience, you'll want to check out Tweet Channel, a simplified, user-friendly interface to working with hashtags. See the most popular channels as well as the newest created channels directly from the Tweet Channel website.

TweetCube - You can share audio, video or images with this. It's is a free file sharing service that lets you tweet larger files to your followers. Just a couple of clicks is all it takes to start sharing files through your TweetCube account.

Tweet2Tweet - What ARE they talking about? With Tweet2Tweet, you can see the @replies between any two people in just minutes. Keep up on any conversation instantly. Just enter both screen names on Tweet2Tweet to see the results in reverse chronological order (most recent entries first). This is a great tool for keeping track of conversations.

TwitterSnooze - With this tool you can temporarily "snooze" a "talkative" tweeter without having to un-follow them permanently. You can set the timeframe anywhere from a day to a month.

Twitterless - Helps you keep track of your followers. This can also be done by simply clicking on the ones you are following, if there is a direct connect, and then you know they are following you as well. This application does the same thing, only it's a little easier I think.

CoTweet - CoTweet lets multiple people at the same company manage their business Twitter accounts together while keeping tabs on their brand name and how it's being used. CoTweet can also be used to assign tasks to different departments and follow up on results and feedback.

OutTwit - Microsoft Outlook is an indispensible part of the day for many individuals, businesses and organizations. If you're like me, you probably have MS Outlook open all day. This application helps you keep up with all you're tweets without having to constantly go to the website and login etc. OutTwit's feature list is too numerous to list here, but suffice it to say that if you use Outlook, you can manage and post to your Twitter account directly from your Outlook interface. You can also track keywords and have the details sent to your email, even if you're not following the original tweeter. Just started using it myself and so far I am really liking it.

TweeTake - TweeTake lets you backup your entire Twitter account into a .CSV file (commonly opened with Microsoft Excel). Back up your tweets, followers and people you're following in just a few minutes. If you have lost followers in the past, this is a must have.

Twitt(url)y - Twitt(url)y lets you instantly see what people are tweeting about and linking to. Track the hot trends instantly. A great source for possible blog entries and new followers since you can see who tweeted or re-tweeted the link as well as the URLs they used. You can also see how often the link was tweeted in a certain timeframe.

TweetWheel - You can see which of your Twitter friends know each other! For large follower base, this will take some time to load (depending on your connection speed) and only does the last 100 followers. I think of this more as a "fun" tool rather than a necessity. It's interesting to see who's following who and just how short the "degrees of separation" are between your followers.

TweetValue - How much is your Twitter account worth? As a sample, Barack Obama's account is worth over $40,000 and Darren's is worth $3,372. Don't ask me how they come up with the values, just another novelty type application.

TwitterGrader - How do you rank on Twitter? Check out your Twitter "grade" out of 100.

Twitter Clients

TweetDeck
Sleek Adobe Air desktop client for Twitter offering a good overview with several panes.

twhirl | the social software client
One of the more popular Twitter clients.

Spaz: An Open-Source Twitter Client for Mac OS X, Windows and Linux
Cross platform open source Twitter client.

Hahlo
Web based iPhone (and iPod Touch) optimized Twitter app.

Twinkle - New iPhone Twitter Client Uses Locate Me Features! | Just Another iPhone Blog
Twitter client for the iPhone that allows you to socialize with people near you. Great for conferences it seems.

Twobile: A Twitter client for Windows Mobile - Download Squad
Twitter client for Windows mobile powered mobile phones. Most smartphones other than iPhone, Blackberry and Google Phone use Widows Mobile.

Misc. Twitter Tools

Twellow :: Twitter Search Directory, Twitter Search Engine
Twellow is the "Yellow Pages" of Twitter.

iTweet 2 : Web
This is an alternative web based interface for Twitter and indeed it's a little more usable than the default one, for instance it offers one click retweets and makes bio links clickable etc.

TwitterCounter: How popular is @photojojo
This is a Twitter followers counter similar to the Feedburner count for blog subscribers.

Magpie: Make Money on Twitter
Magpie is an ad-network for Twitter. It boast that users can make something like 50 to 200$ a month just by tweeting.

About crowdstatus :: Crowdstatus.com
This tool allows you to create address groups of people at Twitter and notify all of them at once.

Twitter WordPress Plugins

Twitter for WordPress - Rick's HideOut
Very basic but unobtrusive way of including your Tweets in your WordPress blog.

Wordpress Twitter Widget
Clean and simple Twitter widget for the WordPress sidebar.

WP to Twitter | Joe Dolson Accessible Web Design
Twitter updater plugin using the Cli.gs short URL service for tweeting your posts.

Adnan`s Crazy Blogging World » Blog Archive » My blog gets twitterized
Basic and quite ugly but very popular Twitter plugin many bloggers use, even TechCrunch.

AJAX Twitter plugin for Wordpress
Advanced AJAX powered widget for your blog not only displaying tweets but letting you send updates from your blog.

Twitter Updater » Fireside Media Development Blog
This tool lets you tweet your blog posts automatically.

Firefox Extensions for Twitter

TwitterFox - naan studio
A popular Twitter Firefox add on. This notifies you of friend tweets.

TwitBin - twitter your browser - twitbin.com
This is a firefox extentions that allows you to keep up with all your Twitter conversations right from your browser sidebar. You can send messages, receive messages, share links, and more.

TwitKit
Another Twitter Firefox client with more features though.

TwitterBar :: Firefox Add-ons
Let's you post from the address bar of your browser.

Twitter Social News

Twitturly - Real-time Link Tracking on Twitter
Digg-like interface for the currently hot tweets.

MicroBlogBuzzes of the last 24 hours
Shows you what's most popular today, this week etc. on Twitter and across the other common microblogging platforms.

Twitturls - Popular Twitter Links Tweeted err Twittered err Twhatever
Shows the latest and most popular links on Twitter.

ReadBurner: What's Shared on the Web
Lets you monitor the buzz around Twitter elsewhere among many other memes.

POPrl.com / Shrinking popular URLs since 1973 / What's POPular
Short URL service like TinyURL but better. Offers not only stats but also a Digg-like interface for the most popular URLs shared.

Twitter Analytics

TweetStats :: Graphin' Your Stats
This statistic tool measures everything from when you tweet (weekdays, time of day) to who your real friends are by counting how often you address people.

Twitstat.com - Twitter Analytics
Both a Twitter search engine and popularity stats at the same time (e.g: showing most active users).

Twitterverse
A Twitter keyword tag cloud for quick overview on what's going on.

Twist - see trends in twitter
Twist allows you to quickly view and compare popularity trends on Twitter. It's similar to Google Trends.

FriendOrFollow.com - Who's not following you back? Who aren't you following?
This tool compares your list of friends with your followers and shows you who does not follow you back.

Twitter Twerp Scan
Gives you a quick overview about your followers so that you don't have to click each one.

HOPE YOU FOUND THIS HELPFUL!  And don't forget, you can follow me on Twitter at http;//twitter.com/midcenturyps

Thank you to Lawrence Brand who posted this on his own Blog,http://twitter.com/mtgmantx