If there's one thing borax does, it's remove gunk and stink from case plastic, without the stickiness that spray cleaners (including Simple Green, in my experience) leave behind. Your mileage may, as ever, vary.
It also hit me reading the Slashdot article (through someone else's mention of using those 'zeolite' sacks for aquariums or car deodorizing) that, once you *have* cleaned as much as you can, you can probably throw a (nonconductive, fabric) pouch of potpourri or related 'aromatherapy' junk into a spare corner of the case... It'd act as a bit of a dehumidifier, and I suppose if you guessed right, you might hit upon a plant compound that inhibits the growth of mold.
Of course, the cheap version of that would be some dry coffee grounds tied in an old (clean!) sock... Charcoal briquettes are supposed to work as well, assuming none of those odors are as-objectionable as whatever you're trying to get rid of.
Or you could just start smoking, then you won't be able to smell anything anyway!
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Edit: Oh yeah, if it *is* from the batteries, try not to rub it all over your hands... Cadmium isn't very nice stuff. (Similarly, if you clip your leaky NiCds, remember to drop them off for recycling; electronics stores usually have a bin for them, now, and it's best to keep that junk out of landfill, or worse, incineration...)
