Among Mac OS X Lion's other fun/annoying iOS-like features is that when you hold down down a key, you're presented with alternatives. For example, holding down n will present you with ñ and ń — handy if you need to type in accents, annoying if you want it to send several keystrokes with a long press. You may really like this feature, but if you don't here's how you can turn it off.
Reader Nick discovered that in OS X Lion, some keys repeated and some did not. Sometimes letters repeat and sometimes they don't. Numbers never repeat. Punctuation and special characters always do. Clearly this is inconsistent, and you might find it frustrating. Fortunately, MacWorld found a solution. All you have to do is type this into the Terminal (found in Your Hard Drive — > Applications — > Utilities) and enter the following:
defaults write -g ApplePressAndHoldEnabled -bool false
Press return and now your keys will repeat as normal. If you change your mind, just change "false" to "true" and you'll have things back the way Apple intended... this time.