This is a perl script. It's portable, as far as I know, it should even work under activeperl as long as you have lynx and mail on your system.
Requires: lynx, perl, mail
Preferrably requires: cron, or some kind of scheduler
You need to change the following lines in the file before scheduling it to run daily:
$username needs to be set to your username
$password needs to be set to your password
$site needs to be set to a site running the livejournal code (by default, it's www.livejournal.com, should work with deadjournal, etc. Untested.)
$email needs to be set to an email address to mail the alerts to. Don't forget to put a backslash before an at sign.
I run this out of cron with the following cron entry:
0 1 * * * $HOME/alertbday.pl
Tested under Debian Linux, should run on all linux variants, and FreeBSD and other BSD variants, Tru64, whatever, as long as it has a working mail command, and lynx installed, and perl, of course.