With the help of my little tree identification book, I misidentified our local hickories as Pignuts - until I ate one. I read that pignuts are usually pretty awful, so I tried one of ours to see if it was a less awful variety, but they were delicious. I did some more research and found that my ID book was not very thorough, and that what we have here are black hickories.
The sap from hickories can be processed the same as maple, but the sap is less sweet. I was considering doing this when I thought we had pignuts, but tasty varieties of hickory nuts sell for $5 a pound (unshelled!,) so there is no way I'm going to steal sap from these valuable nut trees.