Is "Move to Trash" your favorite command? As you work through your day, writing this and drawing that, you generate a bunch of junk—or at least "works in progress"—that you delete as you continue to fine-tune your work. Since you're getting better and better you know that you're not going to want to re-use this stuff; after all, you did throw it in the Trash. But as you know, just 'cause you threw it away doesn't mean that that file or document has really gone away. It just sits there waiting for you to decide what to do about it.
TrashTimer is an app for your Mac that automatically empties the Trash for you. You choose the frequency—maybe once an hour, maybe once a day—and all your junk will magically disappear. Once the Trash is emptied, you get that disk space back, so you can continue to create cool stuff. This tool is a preference panel instead of a "regular" app, so it's not going to take up any space on your Dock.
Since it's a Universal Binary, TrashTimer will run on your PowerPC or Intel-flavored Mac. It runs under OS X 10.3 and later.