Weekly zine/0/Speak
Along with a wide variety of activities installed by default, the XO supports installing activities developed by the community at large. Many of them are listed on the Activities page of the OLPC Wiki; thanks to the open nature of the hardware and software used on the XO, the community of activity developers is large and vibrant and growing daily.
Right now we're going to take a closer look at one of these community-developed activities: Speak, written by Josh Minor. (If you're on an XO right now, you can start playing with it immediately by clicking here and downloading the activity directly to your laptop.)
When Speak starts up, it greets you. "Hello, Phil Bordelon," it told me. "My name is XO. Type something." The voice of the XO comes from the eSpeak speech synthesizer; while it didn't quite get my last name right, neither do most people I know, so that's not much of a surprise. Speak provides you with a large friendly text box for you to enter words into; press Enter and the XO will say aloud what you've typed, with the mouth moving in time with the words.
There's more to it than just this, though; thanks to strong support for multiple languages, Speak can actually say text in a number of different languages.