The one thing that would make me get an iPad today was if it had a USB port. A real one.
I would love to have the iPad to take with me on trips or when I head down to the Smithstonian or maybe to a coffee house to do my writing and then transfer it to my computer when I got home. As it stands now, the only way to do that would be to e-mail the files to myself and then upload them. Can it be done? Absolutely, but it's inconvenient as hell.
Nothing fancy. Just give me a USB port.