A lot of synergy between WoW and LoL.  I would like to see WoW Champions (dev or fan made) in League of Legends.  I'm talking about a conversion game, which means the WoW champions don't play with LoL champions.  Could have dungeons, in addition to MOBAs, even perhaps a RTS w/minions as farmers/lumberjacks/miners and champions guarding the bases.  Like AB in some ways, but instead of destroying a tower like in MOBAS, you capture and hold a base.

Although I feel that MOBAs can be made for a lot of IPs, I'm picking on WoW cause it's big enough, most are familar with it and Blizz might be crazy enough to do it. I have a rough draft of 30 champions, 3 for each class, made into LoL champions here;

http://www.leagueoflegends.com/board/showthread.php?t=965993