LiveJournal.com supports the OpenID distributed identity system, letting you bring your LiveJournal.com identity to other sites, and letting non-LiveJournal.com users bring their identity here. After all, not everybody uses the same websites, but you should still be able to play together.
If you're not a member of LiveJournal.com but want to leave authenticated comments and let people add you as their friend, trust your comments, etc., then you can login either in the form below, or from any comment entry form. Once you're logged in, you'll also be able to read friends-only posts that LiveJournal.com users have indicated you're allowed to read.
If another site says it supports OpenID and you want to use your LiveJournal.com identity there, just enter your journal URL. (you don't need the http:// part either). For example, just enter melody.livejournal.com, or whatever your address is. After you do so, you'll be sent to LiveJournal briefly to ask if you want to trust that site to know who you are. You can either trust them once, or forever. You can change your OpenID settings and trust at any time.