I've seen a few of these on our local craigslist. So far I haven't seen anyone use them for keg serving, but that isn't to say it hasn't been done. The problem with some (most? all?) of these is that the have an internal metal framework that contains the cooling coils. That would get in the way of placing larger items like a keg in it. If you can get a photo of the inside of it as well as the dimensions, you should be able to tell if it'd work for you.
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