I was wondering where should I post slightly off-topic questions. As I've read on SuperUser its only about computer hardware and software. Do the various USB gadgets fit in the 'hardware' category? What about mobile phones, PDAs, GPSes, etc?
It depends on what you're doing with the devices;
if you're talking about programming for devices such as phones or pda's, I'd say thats a SO question.
If its problems using phones or devices themselves, then the only possibility is the electronic gadgets site. If your question is about interfacing it with a computer (sync, data transfer, etc), then you can ask it on Super User, but this is the only case.
If its problems getting USB hardware to work with a computer, SF is a good bet, but again, device specific forums are probably your best bet. Exception being getting data from a device, such as GPS, into a computer program, SO is the best place to try.
Given that you don't state any examples, I'd say put it where you think is apprpriate (given the above) and let the community/moderators migrate it or close it on a case-by-case basis.
Hope that clears things up!