Work with what you've got and use some creative framing solutions to transform your space. We came across this idea via the smart folks over at Young House Love. They hosted a giveaway for MirrorMate, which makes frames that stick on top of any large mirror. At MirrorMate, you can find a frame for any taste and have it shipped to you. The company has committed to being as environmentally-conscious as they can, so that's an added green bonus.
Or, if you're feeling crafty, you can create your own customized look. Try your hand at making one, mitered corners and all, and maybe even utilize some materials that might otherwise be overlooked (extra crown moulding, scraps of weathered wood, etc.).
Will this mirror solution be appearing in your home soon?