Not sure how hard/easy it would be, but it would be nice to have an offline mode for when we're not on the net but want to keep studying. Ideally it would let you download X number of items to the Flash UI and then when you're back on the net it would sync your progress with the server.
I was on a plane yesterday and spent a while using Anki because I didn't have Skritter; a lot of my Anki study could just as well be done in Skritter now, except for the fact that Skritter requires a working Internet connection.
I think an offline mode would probably be much more important when you have Skritter working on cell phones.
James