Publish my library
Publish a list of books that I own.
Lending: This would be nice because people could then ask “can I borrow this book” and then I could lend them the book. I could even mark books as “to give away.”
Reviews: Perhaps also add reviews of books I have read. This would be separate from the list of books I own, though. It could be my own private Idaho Goodreads.
Other media: This could include not just books, but also movies, TV shows, and games, though that might push the scope a little.
It could be neat to publish this in a computer-readable format too: see Library JSON - A Proposal for a Decentralized Goodreads (Tom Critchlow).
See also: