Adam Tow has written (and photographed) a great overview of the history of iPad keyboards:
In the decade that the iPad has been a product, there have been several ways to attach and use hardware keyboards. There’s a goal amongst those in the mechanical keyboard community about finding the “endgame” keyboard. For each individual, this is the keyboard that will be the last keyboard he or she will ever buy. But like a mirage in the desert, the endgame keyboard is an illusion. As with mechanical keyboards, there will be no endgame keyboard for iPad users.
Bonus points for using the original iPad Keyboard Dock with modern devices via an adapter, and bonus bonus points for using the same Viozon stand I use with a mechanical keyboard.
—Linked by Jason Snell