I know he likes chewing/shredding things, and he likes breaking pony beads, but he doesn't seem to like any of the other toys I buy him.

Can anyone recommend something my bird might like?

mine likes to destroy anything...his best fun is ripping stuff apart. I usually take bunches of coffee filters and attatch them to his cage or toss in paper towels and watch him go to town with them. Also coffee stirrer sticks are great as they like to weave them in the cage. Over easter I got some of those plastic eggs bigs ones for the u2 small ones for the littler guys and fill them with treats and close them and they spend hours trying to figure out how to open them (well my u2 has it down pat). I also save plain brown boxes that have no glue on them and stick treats and shredable material inside. My quaker likes bells but you have to make sure they are stainless steel ones even the ones sold for birds tend to not be stainless.
mine also likes to weave with leather strips.

ok. walmart and other arts and crafts stores have a bunch of pony beads for sale and you can usually get the big beads and even a bargain bag full of random beads. i have pounds and pounds of beads from these places. (i used to go to parties a lot and wear plastic jewelry, but now they become bird toys for Grim) also i read that hemp rope is safe to string your toys.

try colorful plastic straws. Grim loves to tear those up and they are safe.