I use the Virtually Indestructable Keyboard here: (2 versions, I use the first one)
http://www.microcenter.com/single_pr...uct_id=0105288
http://www.microcenter.com/single_pr...uct_id=0117712
Not only is it cheap, but if I ever want to clean it, I just take it to the bathroom and plop it in the sink. It took a little gettting used to, but I actually now perfer the 'soft' style keyboard to the typical 'hard' style.
Plus, it's quite the conversation piece. Whenever anyone sees it, they all say the same thing: "Is that your keyboard? Cool..."