depends on what you're looking for. but most good mods in halo require a jtag. but a good site to look up mods is- http://www.thetechgame.com/
If you have Xbox live. Maps on halo 3 for mods. go to bungie.net, make a profile with your gammertag and look for the mods under community. just simply type in mods under the map seciton. it will automatically download to your 360 if you click download on it. I recommend planet mod.
Aimbots do not exist for Halo 3. There are mods for maps though. If you put mods on your file share, it is possible you will be banned though.
its easy download it at filefront.com copy this where halo trial halo 1 halo 2 halo 3 mod mods ok?
ur vajj
As of now the Halo: Reach beta is gone, your not going to be able to.
you go and type on the internate how to mod halo combat evolve and then you download HTML
There are no cheats for halo 3 there are only mods and hacks
You can't install Halo 3 mods anymore to your xbox.
You have to download the mods from the internet onto a flash drive and download the mods to the game you got them for.
http://www.moddb.com/mods/elite-campaign
There are no cheat codes for Halo, only mods.
sorry but other than mods you can't "cheat". you can use as many guides and tips as you like!