Every day I love small window managers more and more, actually I starting to think that there is no need for Gnome or KDE, I am using latelly OpenBox and was using fluxbox before.
One of the differences between these light weight Linux window managers and the Desktops like Gnome or KDE is that when you add or install a new program it is not automatically inserted in the menus, so you need to add it manually or may have a program doing it for you.
If you are using OpenBox you need
First install it.
sudo pacman -S menumaker
sudo emerge menumaker
Once it it installed just run it:
mmaker -vf OpenBox3
For Arch Linux
mmaker -v OpenBox3
For Gentoo Linux.