I owe a lot to Craigslist; I've found jobs, apartments, furniture, roommates, you name it, on the message-board ad site. That's why I relish every tip and enhancement, like adding searches to your RSS Reader or the brilliant Image Preview.
Now here's Craigslist Reader. This download (for Windows only, unfortunately) allows you to search Craigslist RSS-style, and lets you search multiple locations at once for the same thing. This would be great if you're job-hunting in more than one city or are flexible about where you can pick up a wanted piece of furniture.