Some time ago I found, at the suggestion of a friend, a VoIP service I really like. They are http://callwithus.com and they are inexpensive and, more important to me, no BS. Calls between their customers are free as are calls to US and some other toll-free numbers. Regular calls to the US, Canada, UK, China and other places are less than $.01/minute which is hard to beat. The do offer DIDs but not in the US which also appears to me. So, that's my plug them.

For those who like to pay more for a proprietary service, Skype finally has a version out that works with recent Linux distributions. A pleasant change if you have to use Skype.