SD card issues- very strange

So I have the standard 16gb SD card in my phone (Samsung  Fascinate). The problem is that the card shows a total of 14.40gb of space but only 5.5gb available. Now I have moved all my apps to the SD card but I am positive I do NOT have that much crap on my phone to be taking up 9gb of memory. Any ideas? Is there any apps that will weed out any unused crap that  can delete? I have gone through the "files" but am afraid to start deleting anythng because I don't even know what most are. Any ideas would be helpful.

PS: I tend to lose space each time I put a movie or show on and then delete it (a very small space).

Please help.

 It's not cheaply made, but it doesn't have the heft of some other devices in this class (such as the Droid 2). Even the Captivate has a metal back, which gives it a slightly higher-end feel.