Most of the transistors and diodes on these boards are germanium, and may work as replacements in old transistor radios.
I don't know if these boards ever surface at hamfests much anymore, but if you do see them for cheap, you should look for ones with many transistors and diodes. My father used to do computer systems analysis at a big insurance company that used IBM mainframes back in the 1960's, and he would bring home many junked boards like these.