One of the more cost effective marketing techniques available is a blast email. It is possible to use ACT! to generate a template newsletter an send from your own account. The main problem with this is the activity can get you tagged as a spammer. That's really what you are doing, but you don't want your personal or work email account to start getting flagged by your recipients spam guard. Further, there are regulations that you have to be aware of with regard to unsolicited email.
There is a great solution. A third party service will allow you to upload your contact list and then begin your email campaign in earnest.
Once you have your list uploaded, you can proceed with:
* Email newsletter to former clients to keep your name on their mind with regard to your service offering
* Email to a contact list with a service offering that is Target to to their needs
The company I recommend is constant contact which offers a nice 60 day free trial. I am sure there are others
Happy emailing :) And remember the best most cost effective lead is a word of mouth referral!