This offers up 32 possible combinations (including all on and all off) which is enough to cover the modern English alphabet. [Adam’s] demo page works for most tablets so give it a whirl.

Any key found on a standard 104-key can be made by pressing a combination ... with a phone or tablet. The ultimate plan is to make this into a wrist-mounted chording keyboard that extends or ...

As I mentioned in my post about new apps and tools for 2012, I’ve been playing around with a Logitech Tablet Keyboard for iPad, which is available at $69 through Logitech’s website or $59 on Amazon.