Okay... my first map, so I fully expect to flamed. Anyway....
Genetic Research Facility is a single player map, which has you fighting your way through a facility intended to create and research life forms that could prove useful in military action.
Sorry about my over-addiction to rappel marines. This was mainly a map designed to familiarize myself with Half-Life's entities.
I think for my next map, I might make an urban environment (deathmatch map, of course) with two or three houses constructed entirely out of func_breakable brushes linked to fire in sequence (so when you blow out a wall with a grenade, for instance, the ceiling disintegrates, but not vice-versa). It might lead to some interesting breaches. If I do, I'll use custom textures so that they don't come out as stretched as this one did (sorry).