In addition to the previously mentioned virtues of Emacs, I use another feature that I don't commonly find in other editors. Emacs allows you to transparently (through ftp, I belive) edit files on other machines. If you are doing so much cross-development work, then you must be logging into different machines to edit the files you need.

To use this mode, type "Ctrl-x f" to bring up the find file prompt. At the prompt, enter something like the following:
Find file: /user@machinename:/directory/on/remote/machine

This will prompt you for a password and open the directory on the remote machine. You can also open files directly, but I find it most useful to use Emacs' directory mode.

Enjoy!

Edit: Changed "Meta" to "Ctrl" as johnnywang commented on below