The iPad's onscreen keyboard, being virtual, has absolutely no key travel, which can make it hard to type for those of us whose fingers expect the keys to move. Obviously, any Bluetooth keyboard will work with the iPad, but what if you really want to slam on those keys? You need a USBTypewriter, advertised on its site as "a new and groundbreaking innovation in the field of obsolescence."
As the name implies, it's an old-style manual typewriter with a USB microcontroller, and will work as a normal keyboard with any computer. Add the iPad Camera Connection Kit's USB adapter, set the iPad on the carriage, and you have a Typewriter Dock. Watch its YouTube video to see it in all its retro glory.
I was particularly amused to see the USBTypewriter and Typewriter Dock because, at Macworld Expo San Francisco in 2007, when Apple introduced the iPhone, I came across a manual typewriter in the lobby of one of the big hotels. Entranced, I couldn't resist typing "iPhone" on the paper and taking a picture of the old technology announcing the new.
You can actually buy a USBTypewriter for between $400 and $500, and if you have your own manual typewriter already, you can either order a pre-fab kit for $150 or get the USBTypewriter's creator, Jack Zylkin, to customize yours for $200. Or, if you're really handy, you can use the Creative Commons-licensed design documents to do all the work yourself.