By default, the menu on the N900 simply lists all the packages you have in an uncategorised manner. When the list of your installed packages begin to increase, navigating the menu can be a real pain of an exercise.
To bring some sanity to your menu, you might want to install Catorise. You can either use Hildon Application Manager, Faster Application Manager or open a terminal and running as root, type sudo apt-get install catorise.
As the name may imply, what it does is to categorise your installed packages into their group or category.
So for instance, when you install VLC, it is added to the Multimedia sub-menu. This keeps your menu organised, easy to navigate and eye pleasing.