With the upcoming version of Ubuntu (v 10.04 Lucid) the window control (minimize, maximize, close) buttons are placed at the left like in Mac OS. To change their position,
1. Open terminal or use ALT+F2
2. Type gconf-editor
3. Navigate to apps -> metacity -> general
4. You will find a key button_layout with value close,minimize,maximize:
5. Change the order of them as you like (experiment a bit)
:maximize,minimize,close
menu:maximize,minimize,close
6. Done