Here's my idea: High Stake's
The only weapons allowed are pistols and grenades, no kickbacks, no boosters, FFA. Whenever you make a kill, you gain less cash than normal, but you also steal all the cash the other player has collected. The player with the most cash would be marked for all to see so that he would be unable to gather a ton of money and then hide for the rest of the match. Or all the players could have a number next to his/her nametag displaying approximately how much money they had collected (ex. 5k, 6k, 112k, etc...). I'm not sure if it would work, but I think it could be fun.
4 vs. 4 vs. 4 deathmatch
only 92FS - 9mm, AK-47, M4
no customized weapons
only 75% of health, ammo and you can pick only 20 ammos to the rifles at the time and to the pistol only 15 ammos at the time