When I heard GNOME3 was going to get rid of the 'Minimize' and 'Maximize' Buttons, it was no shock to me. I can see how you can argue that it might be a problem for new switchers to Linux but thats another debate.
A) Maximize = Using Left mouse button. Double click on titlebar
B) Minimize = Using Middle mouse button, click on the titlebar
So to do this
1. Get rid of the min/max buttons (I like it on the right side, change it if you prefer left)
gconftool-2 --set "/apps/metacity/general/button_layout" --type string ":close"
2. Set Middle Mouse Click to minimize for title bar
gconftool-2 --set "/apps/metacity/general/action_middle_click_titlebar" --type string "minimize"
3. Make sure is set to Maximize when you double click