Wow...Thanks for the head swell guys...Unfortunately I feel a little embarrassed to be mention in this thread...Within the context of the question I am no where near the level of the people who should fill this thread.
I would have to say Greebo for sure ... along with a few others which I haven't had the opportunity be around much.... the guys who organise and run events on a regular basis I put in there also.... having to spend copious amounts of time trying to put together FSO, Senarios etc and getting grief about little inaccuracies / rules ....I would say, "stick it" half the time.... This brings to mind Baldeagle with his dueling bracket...... and the guys who make the sounds for in game also..... so many.... but all round would have to be Greebo and Fester that I know of that have added to all areas of our game... I am a noob though when it comes to the length of time AH has actually been around.
Just on a side note to get a sense of how much extra time these guys spend on AH .... download the terrain editor and try make a map suitable for the MA....I dare ya....I double dare ya !!