Incidentally, while the earlier link to the "what do I charge" is a good one, most of the computer consultants' discussion has moved to http://openitforum.yuku.com/ -- nice folks, too.

You can also find more data at Janet Ruhl's realrates.com. It is a database where people share how much they're getting for what kind of work. The home page is no longer updated but the database is live with people adding info.