Oo, walnuts, I think I'll try that. I found a can of prune filling which I think I must've bought by accident once (it looks just like poppyseed, except, y'know, for the part about the prunes), and I am going to make some prune hamantaschen this year to use it up, and walnuts sound like just the thing.

I don't mind prune, it's just not my favorite. Usually I make the three traditional-in-my-mind ones: poppyseed, apricot, and cherry.