Remote Desktop spanning two monitors
If you participate in the Windows Vista beta program and you use Remote Desktop, then you might want to have a look at the new RDP client. There's a version for XP SP2 and 2003 SP1.
The main feature that interested me was that it now supports spanning multiple monitors. I've installed it on my XP SP2 box at home, and I can now connect to my XP SP2 box at work and have my desktop span across both of my monitors! I didn't even need to install the new client on my work box to get this either.
The resolution limit is up to 4096x2048