Note: Some sites in the Sources part require you to be logged-in to access the page.
Some Smart Contract (SC) features (lang: Solidity) that I find they are important or interesting:
- Whitelist should be done using SC, not just saving the addresses in the database (Web2 approach). 
- SC can access another SC features, e.g. minting-SC can read the list of whitelisted address from whitelist-SC. 
- SC can be paused if there is an emergency situation e.g. site broke down, leaked SC before pre release date, etc. 
- (Under Ethereum) Creating an NFT? Use SC; Creating whitelist? Use SC; Creating a coin/token? Use SC 
- We can reveal/unreveal NFT images (e.g. in OpenSea) using SC.