Just in case you aren't using them, or if you're using them but want to have c-a, c-e,etc... in many linux desktop apps, here's a little trick.
Open (or create) the file "~/.gtkrc-2.0" and put the following line
gtk-key-theme-name = "Emacs"Save, and open plain firefox. Then in any text field, try c-a, c-e, c-k . Neat, right?
You're welcome :)