One of the best ways to find new marketing ideas is to "steal" them from other industries. Most camp people market the same way, so you need to look elsewhere for fresh promotional ideas.
Here's a tip for resident camps. You can get LOTS of great marketing ideas from the travel industry.
Just Google "travel marketing ideas," "travel industry marketing," or that kind of thing. I'll bet you find lots of great marketing ideas you haven't thought of before, Then you can "steal" and tweak those ideas for your own marketing program at camp.