Blockchain technologies are enableing decentralized financial services. The DeFi market in growing as people assemble smart contracts, as if they were Money Legos. This may impact the banking industry due to the froces of disintermediation.
DeFi has many facets:
Use smart contract development to interact with DeFi protocols. For example, a smart contract that connects with Compound. Deposit DAI and earn say 4% interest. You earn DAI and also bonus COMP tockens (as incentive). Then go to uniswap and swap to COMP to another cryptocurrency. Also borrow currency and earn COMP tokens (which means you can pull 70% of the tokens out). If that works, add leverage by taking out a flash loan. Consider how the interest rates differ. Start small when learning how.
Sablier real-time finance protocol
CoinMarketCap maintains a list: Top DeFi Tokens by Market Capitalization
Synthetix Exchange is a protocol for trading synthetic assets on Ethereum.
AAVEis an open source and non-custodial protocol enabling the creation of money markets. Users can earn interest on deposits and borrow assets.
yearn.finance: earn, zap, APR, vaults.
"The 100+ Projects Pioneering Decentralized Finance – 2020" (categorized list)
DeFi Projects from DeFi Rate
"10 Most Important Companies to Know in DeFi" from Coinspeaker