In addition to the second movie, there are a series of anime being done, with four films available on the net, three have been released so far, with the fourth available in conjuction with Reloaded.
From the beginning, The Matrix has used their web sites very well, including original comix, games, behind the scenes info and so on. The Matrix convinced me to get a DVD player, What Is The Matrix has confirmed my decision to get broadband was correct. And of course, there are the fan fic films.
I can't wait to see Matrix Reloaded.