Direct in Shares (happens almost never for employee participation because the shares always have to be transferred via a notary)
– Economic Ownership Rights (rights to the finances of a specific share)
– Certificates of Shares (Depositary Receipts, either via a foundation or a cooperation)
– Options on Certificates of Shares
– Stock Appreciation Rights

Extra’s but insufficient for most:
– Profit Sharing
– Employee boards to give a vote in the decision making process