Looking for a little telemarketer revenge? The Consumerist has just the thing: It points out that telemarketing companies are required to send you a copy of their "do not call" policy upon request. If they fail to do so, you can sue for $500. The site also points to a sample script from someone who has worked this particular magic.
Another piece of advice: If you have to give out a phone number for a credit card application or contest form or whatever, make it your cell number and be sure to label it as such. If a telemarketer calls your cell, it could be another $500 penalty. (More telemarketing stories.)