Skype for Mac OS X

Via ZDNet:

"Skype Technologies launched a version of its Internet telephony package for Mac owners on Tuesday, as it battles a growing number of competitors offering VoIP products.

Luxembourg-based Skype says it has more than 9 million users worldwide, which puts it at the forefront of the fast-growing Internet telephony market. But it is facing plenty of competition, both from fellow start-ups and established telecommunications providers"