
I rarely use the system menu to start applications. I use keyboard shortcuts instead. Keyboard shortcuts are convenient time savers. To configure the shortcuts I use gconf-editor or CompizConfig Settings Manager (if I have Compiz turned on). Lately I've been using Chromium as my browser. Since Chromium is under heavy development it occasionally becomes unusable and I have to switch back to Firefox. I was hard-coding the browser command in my keyboard shortcuts. This became problematic with frequent browser hopping. I now use the
xdg-open
command when defining my keyboard shortcuts.
xdg-open
opens a file or URL in the user’s preferred application. Below is a screen shot of my keyboard shortcuts defined in gconf-editor on Ubuntu Juanty 9.04.

In the screen shot above notice that in the metacity keybinding_commands I have
xdg-open http://gmail.com
where I used to have
firefox http://gmail.com
Now when switching browsers I don't have to update each keyboard binding command I just change my default browser in Ubuntu by clicking through the menu: System / Preferences / Preferred Applications / Web Browser.

xdg-open
is more convenient for this browser hopper.