I'm a student at the Swiss Institute of Technology. For my fav. games i wasted a lot of time creating new content, ie:
-new tank models for C&C ZeroHour (using 3Dmax)
-maps for C&C
-ini-file tweaking for C&C
-maps for games powered by the Sourceengine (Left4Dead2, Counterstrike Source, Hl2 mods...) (HammerEditor)
-ROMHacks for SuperMarioWorld on the SNES
...(more coming soon) :)