I am sure that as I use my iPad more, for a wider variety of tasks, I'll come up with quite a few features that I wish Apple would add.
Today's wish list item: Viewing more than one app at a time.
Now, I'm not holding my breath for this, really. After all, it took them years just to put true multitasking into iOS. They are clearly trying to create a new interface experience, getting away from the old desktop, window, and file system metaphors entirely. But y'know, sometimes it's really, really useful to see two things at once.
Last night, I was up late writing out some data collection plans on UPad. This morning, I wanted to email another grad student about them - it was really annoying to have to switch back and forth constantly just to get a list of dates from the (handwritten) notes typed into my email. It made me wish I'd just done my work on a plain paper notepad so that I could have it sitting next to my iPad to look at while I wrote the email.
Apple certainly wouldn't have to go back to old style windows entirely to make this happen. It seems that now that there's multitasking, it wouldn't be too hard to have an option to view two (or four) apps onscreen at once. No desktop or home screen behind them, just a simple split screen.
Interestingly, Apple has gotten a patent for what is basically a version of Spaces for a touch screen. While I really really do not see them taking the iPad back to the OS X desktop metaphor as shown in the patent drawings, it makes me hopeful that they are considering some way of viewing more than one app at once. It may not have made any sense for the iPhone or iPod Touch, but the iPad has enough screen real estate to at least offer the option.