In no particular order, mostly jumping on other people's ideas with brainstormy ideas of my own:
Final Fantasy - Potentially amazing, will be tricksy depending on which advancement systems are in play. I will totes help out with this as it develops, even if it's just a wall to bounce ideas off of.
Mecha Fun! - With the recent release of the new BattleTech game, this is hella appealing. I will even go against type and NOT want a real-time fighty-fight thing (mostly because BTMux exists for that, but they have no RP or Aerospace or fun).
Chronicles of Darkness - As someone mentioned above, City-by-Night is hella overdone, and I feel that 'real world place, but with X' could be vastly improved on. My take on that is a Dark City or Matrix approach. The city in which the game takes place is all-encompassing. The matrix speaks about how you do not go on THE highway, and how Neo was in THE mountains (there can be an area outside of the city, to be sure, but there isn't someone from REAL WORLD ATLANTA visiting FAKE CITY-BY-NIGHT.) I other CoD ideas, but this is the most generic and easy to tinker with.
Cyberpunk/Shadowrun - Yes. ALL the yes. Denver is a 19 year old game with more houserules than rules appear in the actual rulebook (possible exaggeration, possibly not), to say nothing of the ooc drama and politics that have gone on there behind the scenes.