blogspot tends to be more political opinion and rants and soapboxes, very journalismistic. (Yes, I just invented that word.)

livejournal seems to be more just keeping in touch with groups of friends by posting about daily life. It's in between forums and blogs, really, but more personal. I like it because I don't have to email 15 people individually when I have news, and they can respond to each other's replies as well which causes a group synergy on some topics like what a good discussion forum will have.

myspace is either people connecting to music or people trying to get popular and get laid.