I have taken to using saren or cling wrap to put around stuff like the front wheel, the seat, handlebars, pedals, and other odds and sods.

I figure that cling wrap, as the next best thing to shrink wrap, is what a LOT of freighted stuff has around it, and it works. It protects items from rubbing directly on each other, and is easier to seal off than bubblewrap -- just rip it off the roll, and that's it!

+1 on checking the size of your box, too. I picked up two from an LBS for our bikes before this trip, but didn't check them for fit until the night before leaving... which presented some problems because the bikes wouldn't fit.

Fortunately, some airlines sell boxes at the airport, and that fixed the issue...