I am posting this from my new XO Laptop. If you've heard of the XO, you know how cool it is! If you haven't, check it out.
OK, so I was just typing a few notes about how cool Sugar (the custom UI) is when it crashed on me =]
Anyway, it's a neat little machine with a great screen, robust wi-fi and absurdly long battery life (up to 24hrs in some scenarios). I got mine via the "Give One, Get One" program. Basically you buy two XO laptops for ~US$400. You get one, the other is sent to a child in a "developing nation". It's a great program - I get to help someone while simultaneously scratching my "cool gadget" itch.
Anyway, after spending a couple of hours with it I think my favorite feature is the complete absence of moving parts. No fan, hard drive, optical drive... the XO is completely silent. I love that.