I’m not a fan of social networking sites in general, but there are two that I have found really useful.

Shelfari

It’s not the first of it’s kind, but Shelfari is a great site for exploring and sharing books with friends. It seems like people don’t talk enough about good books that they’ve read (or maybe I just don’t spend enough time at the bar), so Shelfari seems like a good way to follow what your friends are reading.

Dopplr

Dopplr is one of those sites that I didn’t know I wanted until I started using it (like extra-chunky spaghetti sauce). It lets you keep track of your planned trips, and then tells you when other people you know are going to be in the area. Dopplr can import iCalendar files, so if you’re using a decent calendaring app, it takes absolutely no effort to keep it up to date.

So check out Shelfari and Doppler and look me up.