The password requirements are set up a bit too strict. I would recommend making it a bit less restrictive to encourage people to sign up for the forums.
Hi Zeno --
The reason the password requirements are stringent is to combat spam. Believe it or not, requiring complicated passwords virtually eliminates spam users. We used to get dozens every day, and now get only a couple a month.
I understand that excruciatingly complex passwords are a pain, and certainly not needed from a *security* point of view for a site like this. However, it is truly one of the few changes an administrator can make these days which will stop the flood.