I have all but scrapped the original install of my wpmu and gone again. Things were a little buggy and I figured it was best to scratch it and go again.
WPMU site - Main Structure
with BuddyPress (Gives us topic discussion and facebook style)
Including BP Media (media galleries)
Ability to remove abusive members or spammers
Chat Plugin (LOVE what Paul has been working on!)
Confused as to what all site security / spam options needed as well.
I plan to install Anti-splog
Have installed Support System (but it is in the admin area)
I went gangbusters first time around... Now I just want simple.