The quick answer here would be my newest device, whatever that may be! But my real answer would probably be my Acer Aspire One netbook, which for the past couple of years has been my primary computer. I don't do gaming or anything that needs a lot of bells and whistles, so it fits my needs perfectly. I can read on it (and I did for months before I got a dedicated reader), surf the web, pay my bills, edit my photos, and handle my music library. I periodically back it up to an external hard drive, and I've got an external DVD player for the rare occasions that I want to load software or something. It's never too heavy for my lap, and it will fit into my purse for travel. I'd replace it in a heartbeat if something happened to it.
...among the chocolate and undead (Worldwalker)