Go to a museum, any museum, but an art exhibit is particularly good. Spend 30 minutes trying to make as many different things with a can of playdough or stack of sugar cubes as possible. Take out a box of crayons or colored pencils and try to sketch something. Go to the B&K bookstore magazine rack, grab a huge stack of magazines you never have read before (particularly in the arts section, but really any genre) and flip thru them rapidly, getting fast little impressions. Visit sites like Veer, Computer Arts, graphis, HOW, MAKE, etc. Worth1000 is always a hoot. Haunt the library book stacks, pull out random things and scan thru them.
Do random google image searches using obscure and esoteric keyword combinations.
Play some music you have not listened to for years. Find new ones using some of the itunes or amazon “if you like this, you might also like” features.
Take a walk downtown and look at random things using a little cardboard frame or 35mm slide frame. Or walk downtown with a digital camera and a fat, empty memory card, and randomly hit the shutter on the beat while listening to some music on headphones, without ever looking in the viewfinder. Examine the results later. Take the best five examples into photoshop and start randomly applying every filter you’ve got to the results. Keep a notepad or save out occasional serendipitous results.
Take your public transportation bus line or train all the way to the end of some line and back, take it to places you’ve never been before. Just because. Go browsing in foreign ethnic stores in various neighborhoods. Sit in some public place like a park or terminal, spend an hour watching the people and making up their life stories in your head based just on what you see.
In other words, play with chaos every once in a while.:-)