Firefox Login Add-on
If you use Firefox 2 or above, you might be interested in using an add-on called "LJlogin" which can be found here.
With it, you can easily (and almost instantaneously) change accounts from your personal journal to an RP journal, and back again, or to an unlimited amount of other accounts.
It works with several different journalling sites: LJ, GJ, IJ, JournalFen and Deadjournal. I thought it would be useful to other players.