Freedom Universal Bluetooth Keyboard - ShopCrackBerry
It's pretty sweet. It has a stand to place the storm in landscape mode and turns it into a pretty nice computer-like interface with a 3.5" touchscreen.
I had a little trouble at first with the Bluetooth, but now it works great. I'm still trying to get all the extra features working, but most of everything advertised works. (talking about the shortcut keyboard commands)
It folds up pretty compactly, but it is a little big for the pocket, so I just keep it with me for business meetings and that type of thing. It's the perfect interface to my Storm to make it more accessible for editing office documents since my fingers are huge and they don't have SureType enabled for the landscape mode yet.