A Uniswap-like DEX built on Tezos.
There isn't much yet to play with unless you're comfortable with the CLI, and there aren't many assets live on Tezos yet to start with (aside from a few STOs), but there's already a Uniswap-style on-chain DEX in the making that claims to be positioning for a wave on new projects launching on the chain in the not so distant future.
Liquidity providers will be able to earn liquidity and staking rewards simultaneously, with some thoughts going into dynamically-adjusting fees and a form of governance to let them elect their baker of choice. All formally verified of course.
It seems a little counter-intuitive to build a DEX before a critical mass of tradable assets even exists, but things that take-off are rarely intuitive (or maybe @Camlcase knows something the market doesn't?), so we'll watch this space with interest.
Command-line tutorial