Sweetcode is a fabulous resource either for tools, or inspiration. It's a compendium of unusual software projects on the web, the kind of lightbulb-over-the-head applications that stop and make you think.
If I mentioned all the interesting stuff there, I'd just be duplicating the site. As an example from their archives, LavaPS is a process-tracking program that uses a lava-lamp visual metaphor to give a quick visual gestalt of what's running on your computer.
Go browse Sweetcode, I guarantee you'll find something that will get your creative juices flowing.