Have stuck MAYBE half-a-dozen over the years, and have some comments on what's been posted so far:
Imperial Sizing Die Wax works great--but Forster just sent me a new super-lube that so far in extreme tests has proven to be very good as well. (Will be reporting on on it an article soon, after some more tests.)
Have used all the methods so far mentioned to get stuck cases out, but will note that the last time it happened (when I was testing a new, so-called "fail-proof" stuck-case extractor tool, which didn't work) I couldn't find my old, commercially-made stuck case remover. So went to a local hardware store in my small town and spent less than $3 on the same basic stuff--which amounts to a drill and tap and screw, which did work.
