Cat litter used to increase humidity in cellar (seriously..)?

Yes you could do that, I prefer the gel humidifier because it doesn't have the clay smell of litter and is also sans cat turds. I would think that one should not be so concerned about the humidity of a cellar for several reasons, of which corks won't desiccate like a cigar (there is also liquid in the bottle to keep it moist), and most cellared beer isn't really cellared long enough to warrant this sort of humidity concern. I would be worried about rusty caps and mold and mildew in my cellar room over a few Cantillon corks getting a lil crisp on the outside, or some C&C agglomerated corks drying out past their manufacturer intended best by timeframe.

 

If I needed to worry about hydrating cat litter, I'd just not bother to cellar beers.

In small doses, there are products out there like this:
http://www.cigarsinternational.com/proddisp.asp?item=M-HMC04&stext=jar

I keep one of those jars in my humidor and it works well.