House of the Dead 3 is the best one to use a light gun with. If you finish HotD3, it unlocks a copy of HotD 2. Unfortunately, this "port" of the game (basically from the arcade/Dreamcast version) runs like CR@P on the XBOX hardware. Apparently, noone decided to test (or didn't care) that the game ran so poorly compared to how it ran on the Dreamcast. Oh well, just one more reason to keep my Dreamcast around...lol.
Silent Scope has an "issue" that requires the brightness of the TV screen to be set so high that a lot of the stuff looks washed out. I sold my copy on eBay. This is another example of a game (at least Silent Scope #1) that ran better on the DC hardware (at least due to the brightness/washed out aspects).
Another little known game that can use a light gun is Starsky and Hutch. In a two player mode, player 1 can drive the car while player 2 can use a light gun to shoot the bad guys and other items (pickups/etc.). This game is probably the most accurate of ANY of the light gun games for the XBOX. Once you set up the aim, it is nearly DEAD ON (i.e. little fudge factor for "where" you actually shot as in some light gun games). In other words, if your aim is off, your shots will be too.
Anywho, HotD 3 runs good (even if it's short) and is fun to play. The 2 player mode of Starsky and Hutch is kul too. You can take turns with driving and shooting, makes it more of a "team" effort sort of thing that is fun.