Unless something new has happened in the last couple of days, there is still no option to run the N800 USB controller in host mode. Until this happens (hopefully) there is no way of using a memory stick with it - converter or not.

As for the N770 it should be possible as long as you also use a power injector and/or a (battery-)powered USB hub - this has been described a few times around these forums.

Good luck :-)