The addition of "Collection Disk" are some of my favorite BC releases. Rather than a single game, it's LOADS of games at once.
MAO was a late 360 purchase for me, so I never got to play it as much as I liked. Very good to have it here now! Hope support for the Sega and Namco collections come too (thought he Namco one has the stupid issue of now allowing MP, even on previously MP titles...)
Mutant Storm Empire was a big thing back in the day. One of the stand out hits from the first Xbox's live service, I used to see as much talk for it as one sees for Geometry Wars. I never jumped on the Hype train, though.
And then Tekken 6... some of the worse online experiences for me on the console, though I had an unusually nice amount of friends who got into it. Lobbies would drop ALL the time, matches would disconnect mid-way, and lag was atrocious throughout it's lifetime for me, even after switching modems and routers to try and improve it. I always felt like TTT2 completely invalidates 6, but I'm sure this is untrue for bigger fans of the series. It's actually great to see them bring out multiple games of series, instead of just stopping at certain flagship titles.