The decentralized exchange Sundaeswap is planning an initial stake pool offering (ISO) on Cardano. How does it work and what are the differences/advantages over an ICO?
There is a blog post that describes it quite well: https://sundaeswap-finance.medium.com/sundaeswaps-upcoming-initial-stake-pool-offering-iso-48fade1900a
Basically they will create a Cardano stake pool and you can delegate your ADA to this pool from your Yoroi or Daedalus wallet. The pool will take 50% - 100% margin fee (to fund the SundaeSwap developers). This means you will get less ADA as rewards from the pool. To compensate for this, they will send you some of their new SundaeSwap tokens.
EDIT: There is a more in depth blog post here.
EDIT 2: On 11-JUL-2021 there was an update from the SundaeSwap team. You can read it here: https://www.sundaeswap.finance/posts/iso-update-3
They changed it to a 0% margin fee model that only lasts for 5 epochs. It will be launched together with the DEX shortly after the Alonzo launch on mainnet.