Wondering if there are tools similar to rddesktop for controlling MacOS?

Leam

There are all kinds of VNC variants just for the Mac, like Chicken of the VNC (I am not making that up), RealVNC is very good but costs money, and this says that VNC support is built into Tiger: http://www.macminicolo.net/Mac_VNC_tutor.html

This looks like a good howto, HOWTO Use Your Mac From Anywhere:
http://howto.diveintomark.org/remote-mac/

rdesktop is a special case because it's a free, open source Windows Terminal Server client. Mac and Windows are about as closely related as fish and rutabagas.