USB host mode - Assuming you get 3rd party software or hacked hardware, and then only for FAT formatted flash drives (and doesn't it still pop up a "not recognized" message?). I've added stuff for CD-ROM, and iPods could use mac partitions (which can't be added on, at best loopback with offset works). And cdc_acm for serial/modem/gps and a few others. Do mice and keyboards return things back when unplugged now? A lot of things almost work. And only after some effort on the user's part.

Another big one for me in the browser is there is no "open in new window" support. Some things do (often when I don't want), but when I'm using the RSS reader, it will overwrite the frontmost browser window. A web clipboard of temporary bookmarks would serve the purpose (so I could just keep selecting pages I want then read them in order later).

I'm not sure about the GPS. Something needs fixing, but I don't know if it is me (don't try it indoors), the hardware, or the software.

The camera could be a lot better.