The first is the app's main function, a subtle, on-screen bezel it displays when you enable caps lock by tapping that occasionally-nefarious key. The second is its price: $0.
The free application, featured this week on Apple's own Website, aims to prevent accidental mis-taps that can lead to AWKWARD AT BEST, OBNOXIOUS AT WORST TYPING ERRORS. Don't worry, though, if you totally meant to turn on caps lock, the bezel disappears after a moment, letting you blissfully scream your head off.
CapSee works with Tiger, Leopard, and Snow Leopard, on Intel and PowerPC Macs alike.