I'm a huge fan of Deus Ex and during the release of the first game, I was looking to mod for it.
Firstly I like to mention 'The Nameless Mod', a total conversation for Deus Ex. The story is based off of the PlanetDeusex Community, you play as Treskton, who is set out to search for moderators who are missing in Forum City.
I've done a few maps for 'The Nameless Mod', right now they're in the current stage of beta testing looking bugs and fixing them. Check out the website if you're interesting, as this is the only current total conversation for Deus Ex.
The other mod is the HDTP (High Definition Texture Package) for Deus Ex.
Today's world, computers and consoles are powerful enough to display graphics on HD televisions, developers aim is to create games in High Definition.
A group of artist and modellers has got together to create and update the graphics presented in Deus Ex. Every texture and model will be updated to High Definition, a demo is already out, which updates a few of the models and textures of the game. You can download it here.