There's a new class of so-called 'netbooks' on the market, with more coming later this year. It's not your traditional laptop and shouldn't be confused with one, but it is
an inexpensive way bring the Internet to the SMB wherever you can find a hotspot. Just a simple Internet PC really. Mostly for browsing, internet mail, social networking,etc.
I have a first generation Asus EeePC that goes nicely on top of the doghouse, then folds neatly away when necessary (see below). I take this with me when I dont want to haul the bigger Lenovo ThinkPad. The Asus is selling for about $399 today, with newer versions based on Intel's new Atom processor coming. Acer has the Aspire One out as well, really nice little machine, about same price range.
Remarkably small, fits on doghouse even with plethora of other stuff. Have a small piece of velcro that will hold it here if necessary. Small footprint means it also works well on the countertop above the sink, or anywhere in the SMB really.
Its a small keyboard which is good enough for basic email and such. Fat fingers may be frustrated but again, not for writing your dissertation, more for browsing and basic email. Has a couple of USB ports for a small mouse, other peripherals.
And fits neatly in the basket I keep between the seats. Its the small black neoprene case in between the Atlas and the saw.