Various Marathon netmaps I've created. (A complete list can be obtained from the Bungie.org Archives)
Apocalypse Net Pack (Marathon EVIL Only)
The Apocalypse Net Pack contains two maps: Tornado and Tempest. Tempest is a large netmap, supporting all netmodes. Tornado is more of an arena-style netmap, with a large central area containing the Hill. Both maps support all netmodes and up to 8 players.
Wheel of Evil is a very large 8-player netmap. It includes oodles of aliens for solo romping, and I don't suggest playing this multiplayer with less than about 6 players, unless you turn aliens on ;) Wheel of Evil supports all netmodes except King of the Hill.
(Description taken from the Archives) : A very nice large arena, with a fast-moving peripheral ring. Two rechargers in the center, but if your opponents are any good, you won't be able to use them. In solo mode, the aliens give you a nice run for your money... troopers and hunters regenerate at absurd rates, but enforcers and fighters are on your side to help out. (Careful, though... there are enough enforcers that friendly fire is a real hazard.)