Area Jugglers: THE passing site for passing patterns with more than 2 jugglers - SITE DOWN
Aerial Mirage Jugglers: a promising new site, very well done, lots of material there (and Ralph's page)
Isaac Orr: A huge range of passing rhythms and syncopations, among other passing stuff.
Gandini Juggling: State of the art juggling, and some videos on their commercial site: Media Circus
There is still a passing section on the JIS website
Christophe's site deals with complex theoretical passing stuff. These articles are now available on passingdb.
Aidan's Juggling Page has a passing section
Nate Williams' excellent multiplexes in passing page and videos
Make your own rhythms with Paspat Juggling Patterns Tables.
The passing page of the Mount Clemens Juggling Club (where the Sunshine Series comes from)
Kith passing page
Chan Wilson's passing patterns (including MAJ book in PDF)
Berkeley Juggling Club: a few passing patterns
Wolfgang's site in German
JugglingIJDB (Internet Juggling DataBase): The reference site, with everything you need : texts, conventions, articles, videos (with passing)... and an interface for the juggling Usenet: rec.juggling
JIS: quite out of date, but still a lot of stuff there.
cloons brothers band: Garnav's website with lots of videos.
Olga and Vova have some amazing videos
A shameless plug for my diabolo site & to the Mad French Posse site
SS Ben's Guide to Juggling Patterns will tell you all you need to know and more. You can (and should) also buy the paper copy.