A tablet for reading textbooks.

[CarlosL]

Android is a version of Linux. It has just split off from the main kernel development cycle. (OS X is kind of a version of Unix.)

(Sorry for OT)
Uh, no. Android is not a version of Linux. Android is a whole OS, if you're using Linux to refereer to the kernel, then you're comparing apples to oranges. If you're using 'Linux' to referer to a whole distribution (Linux + GNU + X.org + DE), like Ubuntu or Fedora, Android is not like that at all. Sure, it uses Linux as it's kernel, but everything else is different: there's no X server, no GNU libraries (only a subset is implented) and application software is developed using Google's own SDK. If you expect that you can easliy port GNU/Linux programs to Android, you'll be disappointed. Indeed, Android's C library (Boinc) is not POSIX complaint.