You might already know that on pages like http://www.livejournal.com/update.b
All these links add ?altlogin=1 to the end of the URL - for example: http://www.livejournal.com/update.bml?a
In reality, editinfo.bml does have this, although it's not "?altlogin=1". The following URL does it:
If you're using several journals and frequently want to update their bios, interests, or other information, bookmarking this URL may be helpful.
Update: Please notice that this is the URL that displays a username/password prompt. You do not replace anything in this URL. The percent signs (%) are part of the URL.
Update 2: This is useful if you use several personal journals or shared journals. If you "only" maintain communities, then you can bookmark the following URL directly:
where, of course, you replace "communityname" with the name of your community. This way you don't even need to enter the community's password, but it only works if you're logged in as the maintainer.
Update 3: (sorry about all these updates...) If you go to the following URL, you will be able to edit your own personal info. This, of course, is useless because you can already do that by just going to editinfo.bml. ;)