First off is it a sony Memory Stick or you're just calling it a memory stick because you dont really know what kind of flast memory it is (ie SD, MMC, XD, Memory Stick Duo Pro)

Second what do you want to do with it?
Does it work in your digital camera? plug it into your digital camera
Does it work with your PDA/PPC? plug it into that
Does it work with your PSP? plug it into that
Does it work with your toaster? plug it into that

If you have a computer at work and it has a reader for that kind of flash media then use it to transfer files from your work to your personal computer.

How good is it? think of it as a portable hard drive but smaller (both size and space) and easier to lose.

What can you use it for? what ever you need provide that it's compatable with the card.