Okay, I've had a few hours to de-cynicize and I had a closer look at the LightCap's FAQ, and noticed their suggestions for other uses:

Quote:
Q. Can I put something other than water in the bottle?
A. You bet. The polycarbonate plastic won't absorb flavors, smells or colors (so you won't have to worry that today's milk will taste like yesterday's lemon-aid). But why stop there: you can also stuff it with first aid supplies, a dry t-shirt or socks, camera or cell phone. Remember: it's water-tight?. and it floats!


I bet members here can think of another use or two...

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Another plus, is that it is user servicable - you can change your own batteries:

Quote:
Q. Can I change the batteries?
A. Yes, if you're VERY careful and somewhat mechanical. Simply remove all the screws in the cap (being VERY careful not to lose all the little O-rings) until you unearth the two rechargeable AA Ni-Cad batteries. Change them for new ones if they won't hold a charge anymore (they are good for at least 1,000 cycles-3-4 years worth). Or return the cap to us and we'll do it for you.