Well if you want a good use for them, you can send them to me
Aaaaaannnyway...
Interesting idea, but I dont know a lot about UPS supplies, so I'm not sure how they work. I really doubt you would be able to use them though, because think about the time they take to charge, just to be able to provide, say 20 minutes of power. The chargers were designed for a slow constant supply to the batteries, and probably couldnt handle the large load of a peltier. But who knows if you put a bunch of them together...
Once again, this isn't an area where I have a lot of experience, but this is a new and interesting idea, but maybe it hasn't been tried for a reason.