eldavojohn writes, "Webaroo has added Wikipedia to their services on mobile devices. There have also been open source efforts to deliver it to the iPod (also check out the wiki) or a PDA. I guess if I were still a bartender, this would be a necessity in solving bar disputes before they escalate to fisticuffs."
Wikipedia requires 6 GB of free space, 10 GB recommended. And remember: Don't Panic.