Carry small amounts of stuff in/on your bike;
I found this on a camping site, but realized it could be used to carry stuff for riding.
Use drinking straws by melting the ends to seal them.
This site shows how it's done:
http://briangreen.net/2011/07/diy-single-use-antibiotic-packs.html
For extra peace of mind, put them in an altoids tin or similar.

They also said that the Mio bottles have a good seal and the labels can be peeled off.

latex gloves . . . . take up next to no room in your tank bag or tool kit, allow you to NOT slip greasy mitts back into your brand new high dollar gloves after an impromptu roadside wrenching session.

Good plan.  I carry nitril gloves simply because the latex one fall apart if they get fuel on them. 

+1 on chem lights except keep them in two places.  Some on your bike for wrenching, some (at least one) in your gear.  I always wonder what would happen if I was in a wreck and stuck down a ravine somewhere, how would search and rescue find me???  So I keep a chem light in my gear to signal folks at night.  I figure if I'm in a canyon somewhere, the odds that the bike and I came to rest in the same spot is pretty slim.  I also carry a whistle in my gear.  I learned while backpacking that a whistle is louder than yelling and you can blow into a whistle for hours.  Try yelling for hours and see how your voice holds up.  Plus you can use the whistle for an SOS signal. 

eD

So where do you guys stash your, uh, stash?

In the past.

Well played!