I know my decisions aren't necessarily the most popular ones, but here we go...
#1 - Life's EndWhile Life's End has questionable quality at points, isn't as polished as I'd like, and is by no means native to TWHL, for me it's still the most epic, enjoyable mod ever to be brought to to this site... even if I didn't first find it here.
#2 - Uplink ExtendedUndeniably one of the highest quality mods of all time in the map vault, Muzzleflash's remake of Uplink has all the details you'd expect from a present-day map, and it brings you back to the time you first played that demo, just without the feeling that there was something missing graphically.
#3 ? Orb (Compo 20)While technically not as impressive as numbers four and five, this did one thing that those two didn't: it left me gaping. I have never before in my life seen an entity setup so complex and beautiful as this.
#4 ? Kaufmann HouseWell, Despite Kasperg recently leaving TWHL after creating quite a mess, this still deserves a place in Map of the Year in my opinion. Not only is it the one link to TWHL to be featured in a magazine (!!!), but it was really the defining effort of one of our most remembered mappers.
#5 ? SundenThis was really just thrown in here because I had no other candidates for fifth place, although that's not to say it isn't an impressive effort. It really opened my eyes up and showed me that open-ended outdoor areas were in fact possible in Half-Life, and it?s a great example of it.
For 2007? I have no idea, yet.