I've usually just charged mine at the end of the day and let them sit. Have been doing this for about 3 years now and have not had a problem with anything.

As far as storage goes, mine sit in the same foam lined battery case the NiMHs used to be in. Consider all the hobby shops and warehouses out there that have dozens if not hundreds of them on shelves. If they were that volatile wouldn't we be hearing about these places going up in flames all the time? Wouldn't we hear about postmen being hurt because they have to deliver all the cheap packs people keep ordering from Hong Kong?

I would stay away from metal boxes though. As has been stated earlier, the only problems that I know of occur are after a crash, improper charging, or an "uncontrolled" discharge (such as being shorted out because of some metal.)