You've no doubt seen the split keyboard that iOS 5 brought to the iPad, but it turns out it has a few hidden buttons on the edges. Here's how they work.
My biggest gripe with the split keyboard was that it forced me to type certain letters -- like T or Y -- with certain hands. Depending on what I'm typing, sometimes I prefer reaching to T with my left hand, or Y with my right. It turns out, though, that Apple actually lets you do that with the split keyboard -- you just don't see the keys. Try it: tap and drag the keyboard key in the bottom right corner to split the keyboard, then tap next to the Y key. It should type the letter T. Now the split keyboard is quite a bit more enticing!
[Finer Things in iOS via @danfrakes]