In Twyla Tharp's book "The Creative Habit," she talks about the Box.
Whenever she starts a project, she takes a regular ol' box and starts putting things in it.
She puts in anything that seems to connect to her project - videotapes, books, pictures, objects- whatever seems relevant.
Then when she's looking for ideas or trying to move forward, she consults the Box.
I have a similar habit with regard to my Graphic Novel - I have a basket into which I put images that I find that I think may come in handy.
They include things like interiors of churches and bookstores and libraries, people walking through the forest, and a proper illustration of a motorcycle.
I don't necessarily know how I am going to use all these images, but they strike me and I hang on to them. I tear them out of newspapers and magazines, or junk mail, or wherever they show up. Sometimes I print them off the computer.
They are not just reference material, though - these images create an environment that helps me complete my imaginary world. I surround myself with images that enhance that world, and it gets a little more tangible every day.
So if you're working on something, maybe start a Box or a folder or something, and just throw stuff in there that grabs you or seems relevant. Then, go back and look through it every so often. It can be your very own fountain of inspiration.
One other twist on this: Someone I once worked with had a "Good Guy File," where she put every nice note or email or compliment she got. When she was having a bad day, she'd go look through her Good Guy File. Made her day every time. So while you're making a Box, maybe you can start a Good Guy File too. Such great things to have around.