I have recently discovered that when I look for stencils or inspiration I seem to find the best images through istockphoto, so I went ahead and signed up for a free account. Their search options are very extensive with my favorite being the "color and copyspace" search option below any photo which allows you to specify one or more categories.
Every image I find inspiring I save to my lightbox and now I can go back and remember all the ideas I had while thumbing through these pages.
Here are some of my favorites. I seem to be particularly drawn to colorful retro vectors at the moment.