I have posted about this topic before. It's a great way to have a distinctive bath (typically powder room) but save big on the fixtures. Literally, you can pick up an old dresser or a table at garage sales, flea markets, eBay, and estate sales for a fraction of what you would pay for a new vanity. The look can be as elegant or rustic as you want AND be totally unique.
Tables like this are extra easy because it's open at the bottom. Just cut out for the bowl (follow the template included) and the holes (if necessary) for the faucet. Hook up your plumbing. Note the clever solutions of using a large basket to hold towels.
Dressers are a bit more difficult because they usually have drawers to contend with to fit in your plumbing. You can cut out part of the inner drawer, leaving the face outside. Adhere permanently or use magnets or door hardware. In either case, you'll have a one-of-a-kind bathroom fixture!
[Editor note: Photo is courtesy of A Life's Design. ]