Add both of these links to your Personal Toolbar or whatever your browser of choice uses (they work under Opera, Netscape and Mozilla on *nix and RedmondO$, should also work in IE). The first opens a window where one can type in the LJ username and go straight to the journal. It's been escaped so you can't append things like username/friends because this may well open security holes that I'm unaware of. The userinfo bookmarklet works by either typing into the box or selecting a username (useful when people use the LJ software's "link to users" feature that doesn't make a proper <lj user="username"> tag).
Both of these can be found on my website, along with the formatted code at http://digital.raven.tripod.com/lj_code.html. Enjoy!
: In case anyone cares.