What can you use it for? That's pretty much up to you, and will be limited only by the size of the box you use. Shots of small objects in the studio, on location, items you are selling on eBay, flowers (even still in-the-ground-and-growing ones,) Absolute Vodka bottles for $50,000 ad campaigns, catalog stuff - whatever.
This little thingie does it all in spades - and with a lot of control, too.
The secret is being able to have nice, soft, even light coming from either side or the top - or any combination of the three.
The black and white poster boards serve triple duty as light blockers, reflectors or sweep backgrounds. Not bad for 49 cents, huh?