The graph protocol - decentralized blockchain indexing feeding a network of graphQL servers hosting the data powering dapps https://thegraph.com/en/

Chainlink - decentralized on-chain oracles for basically any piece of data from the real world - https://chain.link/

MakerDAO - creator of the first “soft pegged” stablecoin, it is a series of smart contracts that allow people to lock up crypto as collateral and mint DAI, uses a number of neat and novel mechanisms to keep peg by adjusting interest rates and incentivizing economic behavior https://makerdao.com/en/

Compound - a decentralized lending and borrowing protocol with no centralized authority handling liquidations/collateral pricing/etc. https://compound.finance/

Uniswap - a decentralized exchange for swapping assets in a trustless way, has neat features like flash loans where you can borrow a large amount of money (millions of dollars) for the length of one transaction, as long as the money is returned with a fee. This allows anyone to do things like capture arbitrage opportunities, liquidate large positions, or whatever else can be done in one transaction. https://uniswap.org/faq

A lot of these are DAOs using smart contracts to propose and vote on binding proposals on chain and adjust parameters within the protocol or paying contributors and whatnot. You can see an example here https://compound.finance/governance

Beyond that there’s other blockchains focused on specific use cases like GameFi, bridges connecting together different blockchains and moving liquidity between them in a mostly seamless way, massive research attention being paid to zero knowledge proofs (which have a lot of potential implications in the real world), and multi-sig contracts for only doing things when a quorum of key holders come together and signal their intent.

The general idea is that you precompute a bunch of proofs and store them on disk. Challenges are issued and if you have a matching proof, you can claim the token for that challenge.

The part that I find interesting isn't the tokens. It's the concept that an algorithm can prove you've committed some disk space to the network. The reason I find it interesting is because, for small amounts of disk space, the incremental cost of participation is $0. If I plot proofs on unused disk space and only try to match proofs when my computer is on anyway, it basically costs me nothing.

Compare that to someone trying to farm (aka mine) on an industrial scale and they have a real, non-zero cost starting with the first byte of storage they buy. I find it interesting because it's different than normal economies of scale where a large operator eventually outperforms all the small operators (economically).

Unmatched, but valid proofs, are a byproduct of mining the tokens and those are what proves you have some idle capacity. Since normal PC owners pretty much have to buy excess capacity for something like a hard disk, participating in a system like that doesn't have much downside. It's that byproduct that I think is interesting.

I'm not sure if there are any pragmatic use cases, since the 500GB of free space a normal user has might not exceed the value of pretending to be a real person, but being able to say "I have $50 of idle capacity and I can prove it" could be a novel way to combat large scale networks of bots and bad actors.

[0] https://skiff.com/

[1] https://ens.domains/

[2] https://endaoment.org/