I think it would be very helpful when browsing the map download page, if the map thread said it is Single Player or Coop (just writing SP / Coop. somewhere in the title), so that people can identify fast and downlaod only what they are interested.

Seconded.

Why not split finished coop maps from finished single player maps?

I'm not sure the best way to do this. Adding lots of new categories (Completed SP, Completed Coop, WIP SP, WIP Coop) seems excessive. I'll look into it.

I was thinking more

Single Player
Co-op
WIP
Not a map

I agree with doing that with threads, but I don't think people should put sp_ or mp_ in front of their map names, as that could get lost in the map list. Maybe we should find our own thing to put in front, so everyone knows what it is?
Msleeper, you could possibly force uploaders to select from a drop down box, and whatever they select will go into brackets in front of their thread, i.e.
upload lol.bsp
select WIP from list
Map thread title becomes [WIP] lol

Nightgunner5 wrote:
I was thinking more

Single Player
Co-op
WIP
Not a map

For great justice.

Also look at the tf2maps downloads section if you are too worried sleeper. They have a bunch of categories and stuff but it works out fine.

Nightgunner5 wrote:
I was thinking more

Single Player
Co-op
WIP
Not a map

+1