Garret (sp) was doing a little haxoring to DA a while back. He got bored with it, apparently, and didn't like DA in the first place.
I don't "mod", but I work quite a bit in UnrealEd with level editing. I've also worked in various Quake Editors like Quiver. Along with some old school FPS shit like Marathon. MMMmmm, gotta' love Marathon. That there is the wholesome goodness, my friend.

Hell, I've even worked with TREd, the Tomb Raider Editor; which was pretty sweet.