I've mentioned in the past that I collect advertising postcards and sometimes pick one or more at random to see what ideas come up if I'm stuck. There are also two sites that can help you do the same thing (I found out about these at the excellent 901am.com site, where the motto is, "new media news every morning").
The first is FlickrSpy--you probably already know that Flickr is a hugely popular photo-sharing site, and Flickrspy shows you what new photos are being uploaded at that moment. This means you have a never-ending flow of images going past. If you want, you can grab the image and move it to your desktop (of course you're not allowed to use it for commercial purposes). It can be fun to grab, say, 3 images at random and get your idea flow going by making up a little story that connects the three. Or you can force an association between a random image and whatever you are writing, as I do with the postcards.
The other site is ficlets.com, where people can upload a little story and anybody who wants to can add a prequel or sequel section to extend the story. Again, it's a nice way to limber up. The 'inspirations' page of the site also offers a batch of photos, and suggests lines that could start a story or end one.
Warning: while these sites can help get your creative juices flowing, they can also distract you for too long from actually writing your own thing!
