I still like the altoids tins (mostly because I like the cinnamon altoids that come in them, yummmm, so I have a LOT of them sitting around empty) for making small kits, as well as for organizing small items for my pack, but I do have reservations about the contents getting wet in the event of an unexpected dunk in the drink. I've been experimenting with a container like these:

http://www.anypromo.com/p-677401-swim-safe-box.htm?Source=PLA&gclid=CP2tu7fb7rECFQfCKgodqRUA5g

to keep the contents dry. I came across this type of container during a vacation at a water park (and DW also found some on clearance online and ordered them as well). The altoids tin fits in it perfectly with a little room around it for additional items (I'm also considering using them as containers for BOB fire kits, depending on if they pass the dunking test mentioned next).

A fairly simple test of whether the container will indeed keep the water out completely is to put some paper towels or TP in it and keep it submerged in your bathtub, in a kiddie pool out back, in a pot of water, or whatever you want to use. Leave it there however long you want (until morning, or a day or two), then take it out and open it up. The paper towels or TP will let you know for sure if any significant amount of water has made it in. I haven't tested the case I mentioned above this way yet, so I can't vouch for it's waterproofness, or it's watertightness, I'm still confused which is which, so let's just say I'm not sure it will keep the water out yet.

I'll test these out, sure, but I also like the looks of the otterbox 1000 that someone already mentioned, though they are quite a bit more expensive. My inner tightwad coming out again. Anyway, whatever you come up with or end up using, keeping the stuff inside dry is definitely a plus.

Usual disclaimers, no affiliations with any company mentioned or posted to. As always, YMMV.