I think it depends on the type of game. Visit the Input Lag Wars thread and ask them. Im only passingly familar with this issue. The gamers there can help you.
I think the Philips 5507 has been mentioned as tops for big set input lag, but be advised it uses a Red Chinese Chi Lin panel. Not top panels from LG, Samsung/Sony, and Sharp....so Picture Quality may suffer. However it should be passable, if gaming is a priority.
Vizio VP322 Plasma / Vizio GV42LF LCD / Denon 2200 Silicon Image DVD / Panasonic S97 Faroudja Genesis DVD / Oppo 970HD Mediatek DVD / Oppo 983H Anchor Bay DVD / Panasonic LX-600 Laserdisc / Aiwa MX100 Multi-region VCR / JVC S7600 S-VHS / PS2 / Sega Genesis / Nintendo SNES / Roku 2 XS & HD-XR / Realistic STA-90 Reciever / Realistic Minimus 7 / Antennacraft G1483 Hoverman / Belden 7915A RG6 / Channel Master 7777 Titan 2 UHF/VHF / Panasonic AX-200u / Optoma Graywolf 92" / Draper Luma 92"