Bluetooth Shortcut is what you need if you use bluetooth a lot, and want to be able to turn it on or off as quickly as possible in any application.
Some Samsung phones have a widget built into the notification bar that allows you to toggle settings (powerbar widget notifications), however this is only available on those phones. If you want this just for Bluetooth, then this is the application you need.
You simply have to swipe down the notification bar from within any app, including internet, market, pandora, etc, and you can just tap the notification and you will toggle your bluetooth. Much better than applications that sit on your home screen, because you don't have to be on your homescreen to toggle this one!
Reasons this is better than a homescreen toggle:
1. You can do it from anywhere, not just your homescreen
2. You can see easily on the top of the screen if bluetooth is on or off (different image based on what state it is in)
3. Mimics custom UI designed for samsung phones
If you like this, you can also get Wifi Powerbar, which does the same thing with wifi!