It is funny to me that the primary reason I root all of my Android devices is to add functionality that should have been there in the first place. Android is based on a Linux kernel and Linux supports a lot of cool stuff.
So anyway, today I compiled up the the Linux CIFS module for the Xoom. This allows you to mount Windows file shares on the Android file system (/mnt/cifs by default). With this module (and CIFS Manager from the market) you can access Windows shares like they were part of the Android file system and therefore stream files like movies. Without it, if you wanted to watch a movie on your Windows server, you’d have to download it from the server first, then watch it.
UPDATE: The Tiamat kernel now includes the tunnel (tun.ko) and cifs (cifs.ko) modules. So I have stopped compiling up for every new kernel that comes out.