I have primarily used my xoom for web browsing, words with friends, and attempting to educate the world around me not to drink Steve Jobs kool aid.
Browsing, email (work and personal), PIM, media storage/playback, remote support, various apps, games, etc. etc. etc.
One of my main uses for it though is the convenience. It is much easier to use the Xoom on the couch, bed, girlfriend's back, chair, or lounging around wherever than my laptop is.