Used this for awhile, but occurred to me that others may not be aware.
www.inumbr.com
Free, no sign up, just a quick couple of checkboxes get you a disposable phone number that will forward to your actual phone. Really helpful with newspaper ads, craigslist postings or picking up random chicks who you don't want to know your real number.
You set the expiration date of the number 1 hour, 1 day, 1 week, 1 month etc., and can set specific hours when it will NOT forward to you, e.g. 9p - 8a or something like that. Callers record a short intro message and on the ring through, you can decide whether to take the call or let it go to voicemail.
It's so great because it's literally walk-away...no account registration needed. You don't really give them any information that you cannot fake, except your phone number, and I've read the privacy policy and they don't sell, lease or rent your information. Experientially, I can tell you I've used the service since 2005 whenever I've sold on Craigslist or elsewhere...I haven't had a telemarketing call in 4 years.
Most metro areas can get a number in their area code.
Pretty cool little thing, initially started by Craigslist, and it was called CraigsNumber, but now it's spun off on its own.
Check it out, or post your experiences here.