Social Networking Applications
I'm a Facebook user and I like it. I have a good time finding people I've been out of touch with. I firmly believe, against the admonishment of some, that spending time on social network sites builds relationships with real people. I connect with more people through Facebook...it hasn't made me a lonely geek with zero social skills. Anyway...my soapbox.
Still, I have a hard time really seeing an application of social networking sites like Facebook to my professional work. I'm just not there yet. I just see them at this time as purely "social" tools and I'd rather not mix the two.