I do, its worth every penny, (
well every two pennies!) a minute!
Its lowered my long distance by at least 90%, and I've bought International SkypeIn accounts so my non-Skype using clients can make local calls to them which get forwarded for to me for free.
There's an O'Reilly Hacks book on Skype, buy it, its got a number of other bright ways to use Skype.
The ten euros ($12.00 U.S.D.) lasts me about two months of good CONUS and international use.