The G-Board is a supplementary USB keyboard specifically for gmail, costing $19.99 it’s available from its own site.
Of course it’s not worth cluttering up your desk with this if gmail is something you dip in and out of, or indeed have successfully mastered the 19 keyboard shortcuts that the keyboard has offered; which include “reply all”, “forward”, “star” and so on.
Simple to set up – plug into the USB port, enable keyboard shortcuts in your gmail account and it works.
As USB gadgets go – this is actually a useful one. Though only for hardcore googlemaillers.
$19.99 from Gboard.com