The iPad is synonymous with "tablet" for most people, but that's starting to change. The reason is a crop of fairly well-realized alternatives that offer different sizes, operating systems, and prices. Brian Cooley runs them up to No. 1.
Here's a quick tutorial on how to "root" a Barnes & Noble Nook Color to make it a cheap, capable Android tablet.
And all of CNET's reviews in the fast growing tablet category are here.