Thanks for the tips, folks.   Maeve, that info about using willow-steeped water to help other plants take root is very interesting and likely to be quite helpful.

I did just post a "Free Stuff" ad on Craigslist to see if anyone in my area is interested in the cuttings (the ones with catkins).   There are probably schools and other organizations that do crafts that would like them, but I don't know of any quick way to contact them, so I hope Craigslist will do the trick.