How odd - there's only one bit of JS on there, and that's on the "reset templates" button. Let me know if it happens again.

What do mean "dictate the tags on LJ" - do you mean "have some extra tags defined by the user" that are appended to the automatic ones (or used in place of them)?

If so, then that's a good idea. I'm currently putting in "links" as a default tag, but you're right, letting people customise that would be good.