unfortunately it seems as though most people are not bothering to upload there maps to the "main" mapping sites. it seems as though for the most part, these mapping sites are forgotten about.
imo there use to be "3 main" quality map sites in which to download your maps from, with those being...
1)best one imo was unreal playground, had well over five thousand! 2k4 maps, four thousand UT99 maps and counting
http://www.unrealplayground.com
2)second best was mapraider, this site too had quite a few for 2k4, but not as many as unreal playground
http://www.mapraider.com/
3)third best imo was nalicity, also another quality map downloading site.
http://www.nalicity.beyondunreal.com
all of these places were prime for finding and downloading some of the best custom maps during the ut99-2k4 era, but unfortunately like i said, it seems as though the ball has been dropped as far as people putting there ut3 maps on these sites. just for example unreal playground is closing in on 15,000! maps between ut99,2k3,and 2k4. but barely have 100 total ut3 maps, and i know for a fact much more than 100 maps have been released for ut3 as of now, there could easily be 100 maps for just warfare alone that i have seen around, and i have downloaded prob about 50+ of them. but the maps are just not making it to the mapping sites.
the best place to date for ut3 imo is to just comb the ut3 epic forums in the mapping section and look for maps. i know its time consuming because you have to sort through all the stuff you don't want to look for specific things you do want, but it seems the most amount of content is on there.
also while on the topic of unreal playground, i don't like there new interface at all, i liked the old one much better.