I currently have Quake and Return To Castle: Wolfenstein on my PC.. and I only play custom map for Quake just because no RTCW maps come here... And I also have Quake III and Half Life on PS2 ... and Final Doom on PS1 !!! Yeah, a CD-collection this last one, but always lot of fun while playing.... hem...
Well, like you said, I take a look too at all screenshots from others games, just for interest, and to find new mapping idea...
That's it... let's go mapping... :)) 

atm, it looks like Doom3World's Maps Final forum is the best place to watch for new released maps. They're the biggest Doom3 editing forum there is right now.

http://www.doom3world.org/phpbb2/viewforum.php?f=55

Their Maps WIP thread is also worth having an eye on. Be warned, with their size comes lots of hideous newbie maps and worthless screens.
http://www.doom3world.org/phpbb2/viewforum.php?f=54

We are the Quake mapping center, anything of worth is either posted here, or found by our members and eventually finds it's way here.

Quake2 maps... not sure there's much of a community now, but there are maps posted every so often and I think we see most of the good ones. It appears the community is based here in the two mapping forums.
http://www.bdmcnet.com/forum/


Personally, I've gotten into checking alot of the D3 maps, mostly for my own education. I also check out all Quake, Q2, and Q3 maps posted here. I don't have any other FPS games installed. 

http://www.planetquake.com/musashi

then click on forum, there's a small but quality community there.

I have every game I have installed so I can play custom stuff for anything. But I find with newer games, it's hard to get custom stuff of the same quality as the game so I dont really bother.

So I guess it's really only quake sp, q2 sp, q3dm, UT, Unreal sp, HL sp if the screenies look good. 

Quake(plus mission packs), Quake II(plus mission packs), Quake III(Plus Team Arena) DooM, DooM II, Final DooM, and DooM3 are the only games I have installed. I pretty well check out most things that I come across for Quake, Quake II, Quake III, and now DooM3. Where do I get them from, here, Quake3World, PlanetQuake, LvL, Tikidomain, Mapcenter, DooM3World 

i have a whole load of games installed, but only really play custom maps for quake. and even that, i haven't done in a while because i've been so busy. :\
there's doom3 as well, but haven't for the same reasons (and i haven't seen anything worth playing yet). 

Games I look at maps for: q1, q3, cube
Games I have installed but can't be bothered to look at maps for: q2, ut, rtcw, ss1, ss2

I usually won't comment on a release if I don't load the map because screenies rarely do it justice. I'm not sure what makes the difference between the two above categories. True, I don't like Q2 or UT, but I really enjoy RTCW. 

Right now I pretty much only look at Q3 maps, but I'll probably start checking out Doom 3 stuff soon.

(Also currently installed: Deus Ex, Quake 2, RTCW, Painkiller, Far Cry, KOTOR, Trackmania, The Longest Journey, Myst 3, and Deadly Rooms of Death. :)) 

Quake 1 (duh) and Quake 3 currently.

in the future: add Doom 3 to these two.

In the past and in order of amount of custom maps played [or at least looked at]:

[1]Quake 2
[2]Doom 1/2
[3]Unreal SP maps
[4]Half-Life 

most quake maps, and some q2 and q3 maps that i see on func.

also, sometimes i go to lvl and look at screenshots and (sometimes) download stuff. 

On this rig I have Doom3, Call of Duty, Max Payne 2 and Steam. I'll be getting Quake and Quake 2 back from my old system in about a week tho, and probably UT2k3 as well. 

hi quality quake maps
hi quality q2 maps
hi quality q3 maps
gonna check d3 maps 

There's just been released a SP Doom3 map that supposedly is very good - it's called "Trite Breeding Facility", filename kiltron_d31.zip, available from Fileplanet.

Downloading it just now. Haven't tried it out yet (I haven't even played the original game yet either), it's one map, 19.8 Mb, and the author claims it's "at least 35 minutes of gameplay".

Quote from the .txt file:

"This is an original DOOM 3 map. All my ideas, and all my work to build it. It has been tested on several Nvidia graphics cards including GeForce 6800 Ultra, GeForce FX 5200 and GeForce 4600 TI. You get ultimate performance in this level using the recommended card for DOOM 3 which is the GeForce 6800 series of cards. Using the other two cards the level played well, but the FPS was very low in certain areas." 

Welcome to this morning's news =)

http://celephais.net/board/view_thread.php?id=21912 

Q1 - I look here.
Q2, Half-Life - I go to [ten four] but it hasn't been updated in a long time
Unreal and UTSP - UnrealSP.org
Undying - Standing Stones (very quiet - not surprisingly)
Deus Ex - PlanetDeusEx
Duke3D - Planet Duke (I had a fit of nostalgia this summer after finding a win32 port)

I have bookmarked a few interesting Half-Life and DeusEx SP mod sites awaiting completion.

I have heaps of DooM wads and Q1 and Q2 maps but pretty much all other games except for Unreal have nowhere near the number of single player user maps. I prefer to get maps from trusted review sites as I don't want to play buggy or ugly maps. I hope a quality DooM3 site exists by the time I get and can run D3 as I prefer filtered maps. Of all the games with user maps, Quake by far had the best selection of acceptable review sites with TeamShambler being my staple during its period of operation.

I also prefer review sites over open forums as they do the work of searching and screening for me and hopefully, only offer up maps that approach or exceed those made with the shipped game. They also usually have a nifty news front page so that it's one click to see if anything new is out. I'm lazy, you see. 

Well i have these games Installed currently:

Battlefield 1942
Battlefield Vietnam
C&C Generals: Zero Hour
Halo
Call of Duty
Doom 3
Half-Life
Quake II
Quake III
Far Cry

But honestly I've only checked out custom maps for Quake III, Far Cry & Doom 3 recently. Granted there hasnt been anything really worth looking at for Doom 3 yet. And actually have downloaded a few custom maps for C&C Generals: Zero Hour.