well, Live Journal is an online journal. It's free and open source (meaning the code/construction are public), and very simple to use.
MySpace is also an online journal, but it's more focused on connecting you with other people to chat with.
Blogs (online journals) are an EXCELLENT way to keep in touch with people you don't see very often and strictly online friends.
You know those friends of urs in Blah-country whom you haven't seen in years and often wonder about? Well, if they had blogs, and you had a blog, everyone would be all up to date with what was going on in everyone's life and there wouldn't be one penny spent on akward long-distance phone calls.
Blogs can be as personal or as non-challant as you'd like them to be. I've got friends with more than one blog too - one for info on their tanks, one for info on their lives, and one for political discussions. I tend to lump everything all into one journal, but you can configure it any way you'd like.
Check out MySpace, Friendster, LiveJournal, Xanga, Facebook.... there are hundreds of them, all unique, each with their own 'crowd' and set of kewl bells and whistles.
I think EVERYONE should blog! :cheer: