I use Ubuntu 10.4 with Gnome and this has always drove me nuts:

Why can't I copy/paste/delete files from the "Open File" or "Save File" dialogs?

When I used to use Windows, I had to do stuff like that all the time: before I could save something, I had to do a little bit of cleaning and rearranging and it was very convenient for me to be able to do it right there in the Save File dialog as opposed to having to go into a file explorer or use the terminal.

What's the deal with that? I just think it should be a standard thing for Gnome/Nautilus.