I hid two items by using the '1' hotkey, and now I can't figure out how to get them back. I don't remember what they were called, so I can't find them in the Cell View window. The wiki isn't providing much help in this matter. Ctrl+Z isn't working.

According to View->Render Window Hotkeys, you can use 'Alt+1' to unhide all hidden objects.

Yes, thanks! That worked.