So I went out looking for some custom maps and found a few that I enjoyed playing. Now, in an effort to save bandwidth, if you want to play on this server, you will have to download the custom maps first.

Don't worry, I already went ahead and placed them together in a ZIP file at your convenience here: http://drop.io/escapistasc/asset/swarm-custom-zip

Once these are installed, you'll be able to play on the server no problem. Some of the survival maps are pretty intense as well. Hope to see some of you on there!
Installation Instructions

Most maps and campaigns will come as a VPK file. VPK files are Valves version of packed add-ons and can usually be installed by simply running or double clicking on the file. If it doesn't run and you get a dialog saying "Windows can't open this file" you have 2 options.

Option one is to check "Select a program from a list of installed programs" and hit "Ok". This will bring up a new window, click "Browse" and navigate to "Steam\steamapps\common\alien swarm\bin" and select "addoninstaller.exe".

If you checked "Always use the selected program to open this type of file" option then from now on all VPK files will now be automatically installed when you double click them.

Option 2 is to copy each file to "Steam\steamapps\common\alien swarm\swarm\addons" and your map/campaign will be installed. Downside to this option is you will have to do it for each VPK file you download.

After you have your file installed you can view and manage it in-game via the Options->Add-ons menu.