What I do
I have been mapping since early in half-life 1. Most of my work was for Opposing Forces, Half-Life Deathmatch, and Half-Life Elite. I really focused on balance and how weapon placement and map geometry effected how players choose to play a map. I also worked really hard to remove exploits and bugs in my map. As far as I know I may have been the only mapper who would design my maps to have almost no tau reflection.
I taught myself to code so I could help the Half-Life Elite modification for Half-Life 1. This was a fun modification which did not really take off due to an already established modification. Many of the features originally conceived and implemented in HLE would later show up in other mods like Adrenaline_Gamer and Half-Life_2_Deathmatch:_Pro. I also took the opportunity to fix most of the bugs and exploits that had bothered me as a mapper.