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A local recycling drop-off location also accepted batteries.  I was dropping some old alkalines when I saw a green light start glowing in the drop-off bin.  I dug down into the pile of old batteries and pulled out about twenty MacBook battery packs that still showed full charge (according to the little green lights).

I took them home and opened one up to see that the lithium ion cells were 18650 style.  The battery on my laptop hadn't worked in months so I decided to swap the dead cells out of my current laptop pack with the ones from the salvaged MacBook packs.  With some careful soldering, I was able to swap the cells.

The loss of power reset the microcontroller on the battery pack so it assumed that the cells were brand new.  After a few discharge/recharge cycles, it leveled out at about 80% of the packs rated charge.  Not bad!