I am really picky about which ones I use for my actual journal, but I use "journal" books as all-purpose notebooks, too ... jotting down whatever weird and random stuff I can think of. I kept one journal full of questions I wanted to look up or think about in my spare time. (Lame, but I am always forgetting if I don't write things down.) I kept another journal with financial info, another one with grocery lists, another one with quotes I stumbled upon that I loved and didn't want to lose ... I dunno. I just like having them sit around on my shelves, too. I'm a lazy, shameless journalaholic.
I also feel this horrible urge to announce that I detest the color purple. And unicorns just bug me.