There are modders and hackers that like to tinker with just about everything under the sun. When there are restrictions, it is taken as a challenge. However, when the proper tools are provided openly, some really amazing things can come of it.
The Darkmatter Xbox Laptop and DIY kit is the first of its kind. It is open source, and can be purchased in kit form, or fully assembled. It will let you use controllers wirelessly, can hook up two wired controllers, has a headphone jack, HDMI port, and internal 3W speakers. It’s made of laser-cut ABS plastic, and will play nicely with your Kinect. There are a variety of options to choose from, ranging from $149 with a few pieces of the kit to $1000 which will get you the finished product. Although, I would think it’s a bit silly to buy the finished product if you just want to play with its innards.