Voice-over-IP phone service
Skype have started offering dial-in phone numbers. This means that, for a regular fee, you can rent a phone number in one of several countries and area codes. People calling that number will get through to your Skype client, and will pay only the standard rate for calling a number in that area. Currently, there are phone numbers available in the US (various area codes), the UK (London), France and Hong Kong; hopefully more countries will follow soon.
SkypeIn information is not yet visible on the public site, but if you log in, it offers to sell you a phone number or three. I wonder how quickly they will run out of numbers.