Can we try to contact that Simon O' Callahan and ask him if he would like to create a map for the second OACMP? His maps are impressive...
About eyecandy... I think that insteresting things can be done also with the classic Q3 shaders.
Take a look to the attached file, I've made a compilation of "cool" Quake 3 views (good-looking places with interesting shader effects).
OA maps may include more eyecandy, as including more
- force fields
- "living" walls, "pulsing" plants
- Shining doors with futuristic design
- Shining walls and floors
- blue illumination while underwater
- monitors with refections and/or animations
- floating spotlights
- fans
- shining glass
- control consoles
- skeletons
- cool teleporters and portals
- mirrors
- fog
- moving gears and machinery
(Of course, for OA3, following the artistic direction Fromhell will like)
More, we have optional GLSL (but it's not used in real maps yet... and there isn't a GUI option to enable it yet), flares (but I keep them off because they are distracting) and bloom (But I keep it off because it hurts performance) support.
By the way, an OpenArena map I really appreciate for its attention to eyecandy is PUL1DUEL-OA ("Five steps ahead"). That one looks really nice, IMHO. I think that having one or two more maps with such graphic style would be good.
PS: What about a "frozen" style map, like
this one (never tried)?