If you like the look of natural stone fireplaces, then you'll probably dig this "Gorge Stone" surround. Here's the kicker though: it's not made from stone at all.
The veneer is made from recycled concrete and sand.
"Formed to resemble natural Columbia River basalt, Gorge Stone has been created as an earth-friendly alternative to stone veneer products."
It can be used for retaining walls, decorative stone walls, and--of course!--fireplaces.
You can get square and rectangular "stones" to offer variety, and the veneer thickness ranges from 1.5" to 3". Since it's not real stone, you might even be able to install something like this on your existing fireplace--just in case you're looking for a face lift without a huge tear-down remodeling job.
More information at Gorge Stone.