Does anyone know of a Firefox plugin that would enable tab-completion (or some other key sequence like Alt-L) of items in drop-down lists in web forms?

e.g.

ou<TAB>in<TAB>s<TAB>

for 'OurCompany - Internal Support'

Vimperator's hints mode makes it very ergonomic to focus the drop-down list with a key sequence like

f13

but the keyboard interface to the drop-down list still sucks. I very frequently have to pick items from a very long list with very long common prefixes among the entries (e.g. 30-40 starting with OurCompany -), which renders both the built-in keyboard interface and the mouse pretty slow and unergonomic.

I basically want readline support for filling webforms!