I have a group of buddies who run a Unreal Tournament 2004 server, but it's run on an ADSL connection with terrible upload speeds. It's enough to support about 16 in game players, but maps only download at about 10 Kbps. Is there any way to configure the server to serve the content from a secondary server, such as a free web host? I know that the source engine has always supported this, and it would be nice if Unreal did too. My googling yielded no results though.
I know this is a late answer, but I'll answer anyway.
You need to edit your server's .ini files to add a proper HTTP redirect. Any requests to download mods and maps will be redirected to any server you want. As long as the host you're linking to supports direct downloading, you'll be fine. I recommend Dropbox Public folder.
There's a complete tutorial available here: http://wiki.unrealadmin.org/Redirection_and_Compression