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.
Panasonic AX-200u / Optoma Graywolf 92" / Draper Luma 92"
Samsung 51F8500 Plasma / Vizio M422i LCD / Vizio GV42LF LCD / Vizio VP322 Plasma
Sony S790 BD / Panasonic BDT220 BD / Roku 2 XS & HD-XR / PlayStation 3
Oppo 983H Anchor Bay VRS / Denon 2930CI Silicon Optix Reon / Panasonic S97 Faroudja Genesis / Oppo 970HD Mediatek
Panasonic LX-900 Laserdisc / Aiwa MX100 Multi-region VCR / JVC S7600 S-VHS