Oct 31 @ 8 p.m. Webster Hall turns into Webster HELL for the official post-parade after party. All four floors will be filled with sexy monsters and freakish ghouls (and probably some Michael Phelps swimsuit costumes thrown in for good measure). The night's best get-up nabs a $5,000 prize (!!!), awarded at 2 a.m. Open bar: 8-10pm. Price: $25 entry; 19 to enter, 21 to drink.

Webster Hall - 125 East 11th Street (btw 3 & 4 Ave), 212-353-1600