Below please find links to useful e28 information.
M535i.org Contains lots of information on the m535i e12/e28 models as well as information concerning the North American market 535is and lots information on e28s in general.
Team DFL Lots of good stuff about prepping your e28 for high performance. Ed did quite well with his very capable e28 in SCCA racing.
If you have another link you think would be useful to the e28 community, please either make a post in General Conversation about it or let one of the Beamters know via PM.