I'm a fairly new Mac user after decades of DOS and Windows use, so it may be that many of my minor gripes are just ignorance. But my big things are:

1. No recurring tasks in iCal. I used to use them all of the time, and I really dislike Entourage. I'm hoping that this is improved soon.

2. No way to restore files to original locations in the Trash. If I delete something I have to remember where it came from to drag it back?

3. No way in Finder to empty the trash for a particular disk. If I have just deleted files on a USB drive, I may want to empty its trash, but not the trash on my hard disk. I know, I can do this with Pathfinder, but there are things about Pathfinder that I do not like. I'd prefer it if Trash was just smarter this way.

4. The way that shift-arrow works for highlighting text is counterintuitive to me. I'd prefer it if I could just work on one direction at a time - shift-right to extend the end, shift-left to reduce it if I overshoot.

It is interesting to read other people's gripes. Some things are just no big deal to me - like ejecting external drives. I've always done it that way anyway, in Windows, Linux, whatever.