A company called Numbr is offering an amazing free service. Just follow the Free Privacy Numbers link to create a free phone number that will forward to your own phone.
Use it for selling goods on craigslist, bar crawls, avoiding telemarketers… any time you need to protect your real number.
You can play with options about when your number expires, when calls can come through, whether you want to be able to screen.
All free.
Numbr.com:: Home Page
Looks like the free version of this is gone. Oh well.