What is the CSUAC?
If you are currently a mapper or plan to do any mapping in the future, there is one resource above all others that you will want to have. Cecil Solomon's Ultimate Art Collection (CSUAC) is a collection of .png files divided into sections and designed to work with all three of the major mapping programs (Campaign Cartographer, Dundjinni, and Fractal Mapper).
The zip files are on the order of 650mb and contain many thousands of quality images. They are separated by category into symbol libraries that can be accessed directly from within each program. The files come from many sources with the bulk being collected from the Dunjinni User Art Forums. All of the images are free to use for non-commercial uses.
Where To Get The CSUAC
Most of the sites that used to host it have disappeared. As far as I am aware, it is now available only from the originator's site: GM's Apprentice. Note that this site looks to have been abandoned for the past year and a half so who knows how much longer it will be available. Go get the files while you can!
You must be registered and logged in to access the download areas at the GM's Apprentice. I had trouble registering (and apparently so have others). It doesn't seem to like user names with spaces, underscores or special characters. When you attempt to register with a user name it doesn't like, nothing appears to happen so it looks broken. Try another user name. Bad, or already in use, emails or passwords may cause a similar problem so just keep trying alternatives if you have trouble registering.