useful *.bro files repository?

Vern and all,

Bro is up and running on our site, thanks to this list for the help with
the compilation!

I was wondering if there is (or SHOULD BE) a repository of useful *.bro
policies to use for different cases. Right now I am running with '@load
mt' and some other @load's which I semi-intelligently selected from the
policies dir, but I noticed there is a bunch of other fun bro files. Which
of them are useful and when?

Also, I understand that rules.bro is undocumented, but can I get ANY hints
on its functionality beyond what I can figure from looking at the files

BTW, I was also about to ask how to best collect and analyze alerts, but I
my have an answer to this one. Our product might soon collect Bro alerts
and report on them (in the context of other security event messages).