not sure how many of you have heard of this, but my dad pointed out a website to me yesterday. it's the US government's "do not call" registry. basically, you go to
this page, fill out a form with your phone number and email address, click the link in the email they send you, and then a huge list of telemarketers is blocked from calling you for 5 years.
it won't help with calls from survey companies, charities, political orginizations, or companies that you've given your phone # to (i.e. you bought something from them and gave them your # as part of the transaction), but it will stop cold calls from people trying to sell you stuff (loans, mortgages, credit cards, real estate services, random products, etc).
Paul