Kitchen computers aren't especially cheap as of yet. However, if you have a laptop you can dedicate to your kitchen, you can create a kitchen computer for only a few dollars. This Instructable by project109x turns the laptop upside down, and uses a wireless keyboard and mouse to make the setting flexible.
Having it upside down (and in this case, in its own dedicated area) makes it far less prone to suffering due to spills. Add the Belkin Washable Mouse and the Unotron Washable Keyboard, or the Bendi Keyboard, and you'll be in the clear from kitchen dirt and junk.