Without buying a pricey "squirrel-proof" feeder that may not live up to its promise, hot chili is a good way to foil greedy, destructive squirrels. You can buy additives for wild bird seed at the feed store, but it's just hot pepper/cayenne in different, pricier packaging. Mix about a half-cup of it into 10lbs of seed - shake it up in a well-sealed container and don't open it right away unless you want to sneeze and gasp as you dab your burning eyes. Birds are unaffected by it but squirrels won't bother your feeders. I don't know iwhether or not other rodents share that aversion.
It's not that I want the squirrels to starve - I do put out cheaper seed, and bread, for them. I just don't want them monopolizing and chewing up the bird feeders, in which I use shelled sunflower. Another idea I came up with that works to slow the squirrels down is to fill empty milk cartons and the like with seed, then water, freeze, then peel off the container and put the frozen block outside, where the squirrels will gnaw at it rather than scattering seed all around. I also use ice cube trays or styrofoam egg cartons to freeze unshelled peanuts and other nuts into ice cubes for the squirrels.
Any other low-tech ideas for wildlife feeding?