Okay, so you need to sell something on Craigslist, or put a classified ad in the paper. You want people to buy your item, whether it's an old couch, or a late model used car. The only way you're going to find out who wants your stuff is to give them a phone number in the ad. Great, now whether you make your sale or not, you're going to be plagued with junk phone calls, because your number is out there in the wild. You can get throwaway email addresses to use in situations like these; what about throwaway phone numbers?
Freedigits is a service that lets you do just that. Not just another Skype knock-off, Freedigits provides you with an unlisted US phone number, where you can take calls from real telephones, and not just other members, like with Gizmo. After free registration and instant activation, you can download a "soft phone" for your Windows or Mac system, and start receiving unlimited calls right away. If you are away from your system, or don't want to pick-up in real time, no problem: integrated voicemail will email you an MP3 of any calls you've missed. You can even make 60 minutes worth of outbound calls for free, as well as unlimited toll-free (800, 888, 877, 866) calls as well. And hey, you know that your phone number shows up when you make toll-free calls, right? Even with caller ID blocking. Here's a number that isn't tied to you, so there's no way you're going to get junk calls back on it.
Freedigits is a free service.