My journal is called Helen's musings on life etc. because... Well, because that's what you get. Anything I fancy putting here really.
My subtitle is _____ because _____.
I don't have one. I either didn't notice the option when I set up my LJ or (more likely) couldn't think of one.
My friends page is called Helen's Reading List because that's what I think of it as. It's a collections of writings I like to read. Friend implies a mutuality to the relationship that doesn't always exist. There are people whose journals I read, who don't read mine. I'm perfectly happy with this. There are a few people who read my journal who aren't on my Reading List. Possibly due to time constraints (I do read my Reading List and I don't have much time to do it in), but more likely it's because I haven't yet managed to find one of those round things, you know, a Tuit.
My username is llygoden because I really would have liked "rat" or something rat related, but the obvious ones were taken, as was "mouse", naturally. So I turned to Welsh for inspiration, but "rat" in Welsh is llygoden fawr, basically "big mouse" and rather cumbersome, so I went with llygoden. Besides, I felt a bit mouse-like and timid venturing into a new medium.
My default userpic is a mouse, for obvious reasons and, as I needed something quickly at the time, I found the one I use somewhere on the web. I think it's quite cute.