The only thing I use my journal for is collecting links to things I might want later. I had an actual notebook for that, but writing out long links is pretty tedious, and I'm constantly expecting myself to screw up without noticing. Having it on my Gaia account makes it feel more portable, too.
I only ever refer to journals when I invite people who rant and don't accept counterpoints to use them so nobody would bother them with the junk they put in there and the material is definitely away from the rest of Gaia...that's a good thing btw.
I use my journals to display my various avis, art from various thread, and posting styles. I think I also have one displaying my allegiances from various gaia plots.
I used to use it as a tumblr like thing where I just posted my (then kind of crappy) art. lol. I haven't used it since you had to use it to get a bunny in the Easter event last yeah. ...I do like reading Dev/Artist journals.
Storage. No matter what odd s**t goes down with my computer, I'll always have a backup document in my journal.
I use it a lot for saving my profile codes, especially. It's really convenient! emotion_yatta
I don't read journals much, unless an entry is brought to my attention or referenced in someone's post.
I kept up with Fayren's journal pretty consistently for a long while, though.