Remote desktop clients for Mac OS X.
If you want to check out clients for a different OS, go back to the Remote Desktop Clients index.
If you're looking for servers, go to the Remote Desktop Servers index.
Microsoft has an OS X client for Remote Desktop:Microsoft Remote Desktop Connection Client for Mac 2 [Mac OS X]
Ericom has a client that supports accellerated and compressed remote desktop. A free trial is available from their website:Ericom Blaze [Mac OS X]
There is also an open source native OS X client called CoRD has been developed by Craig Dooley and Dorian Johnson. You can get it from sourceforge:CoRD Remote Desktop Client [Mac OS X]