I recently received a phone call from a phone scammer. This one was related to domain name renewal. But as you know there are many others out there: mortgage scams, insurance scams, etc.
I did a reverse search on the phone number and found some interesting links. This includes forums where other people have received the same call. One of the best resources I found was Who Called Us.
Who Called Us is a sort of reverse directory of "UNAVAILABLE" phone numbers. It's better than a typical reverse phone search because it includes phone numbers of scam artists (not normally listed in the white pages). In addition, you can review others' comments to see what they experienced.
NOTE: While writing this post, I just received another call from them.
So there you go... Another resource to put into your arsenal of tools to protect your clients and yourself.
Update: Three calls so far this morning (all from the same people). I've reported them to the FTC.