BOINC Confederation

Back in 2015, someone created a series of Bitcoin addresses, each funded with an amount of BTC, and each with its private key deliberately restricted to a known, sequentially-numbered range: puzzle #1's key is somewhere in a 1-bit range, puzzle #2's in a 2-bit range, and so on up to puzzle #160's 160-bit range. It was set up as a public challenge: whoever finds the key for an address can claim the coins in it, using nothing but publicly available information. Most of the small, early puzzles were solved years ago. Many of the larger ones are still unclaimed today, some holding real value, and that's what bitboinc is for.

Eternity II — community computing

This project seeks a complete solution to the Eternity II puzzle. Your computer processes CPU computing units, and each result is verified before being integrated into the search engine.