Zoom IN and Zoom OUT are so important functions in a mobile device with a physically small screen, that they deserve keyboard shortcuts in a A-Z part of the qwerty-keyboard.

I've proposed this to Fennec people before, but no comment.

Ctrl+I for zoom-in and Ctrl+O for zoom-out (or without CTRL also if we are not in the input mode).
Also CTRL+H for left translation, CTRL+U for up, CTRL+J for down and CTRL+K for right translation/panning/cursor_movement.

One could call these, HUJKIO-extension.

For example in scandinavian version of N900 qwerty of N900, up/down arrows are behind Alt-key, so for the current Fennec zoom-in/out shortcuts one should press three keys at the same time. Not a good choice for a keyboard shortcuts there.
Most used shortcuts deserve the reservation in A-Z part of the key-sequences.

For zooming and panning, I can't think better shortcuts than HUJKIO, if one just examines any small device physical keyboard. For easy and quick panning and zooming, having HUJKIO-keys for those is egonomic, with or without CTRL-key.

btw, for example Xournal program uses 'I' for zoom-in and 'O' for zoom-out, good.