Bimmer Forums is a very popular BMW Discussion website. They have General BMW Discussion, events and rides. They also have turbo engine discussion, Auto cross and drag racing etc. If you own on just like BMW then there is plenty to see here.
MrCarGeek Pros for Bimmer Forums
Lots of content and fast response
MrCarGeek Cons for Bimmer Forums
I wish the site had more bells and whistles