T-hawk
Transcend
I spent a little while making some small, unobtrusive tags for the resources in C3C. Luxuries get a happy face, strategics get an identifying letter, anything else is a terrain bonus resource and doesn't really need identification.
http://www.civfanatics.net/uploads6/resources1.pcx (rename it to resources.pcx and put it in Conquests\Terrain)
In-game screenshot:
http://www.civfanatics.net/uploads6/resources1.pcx (rename it to resources.pcx and put it in Conquests\Terrain)
In-game screenshot: