Map: JusTiN ( back in the old days, he used to create many nice maps!). I wonder what he could do if he still played the game. The editor now is much better so he could make even more awesome maps. Also i like KimKat's maps, he is a genius with lua + map.
Skin: Scyther, but there are many more good skinners on the forum here.
Tile set: JusTiN, blazingxx( I remember his cs2d source like or sth, it was pretty good.)
Lua Scripts: Lee ( theoretical king) , weiwen, and the person who scripted the warcraft mod.
serverside programming: TMK indeed. He is just a genius in decoding packets.
and hmm, i'm not gonna mention other modifications.