Aside from typical bounty campaign and airdrop. Now the hype change to incentivized testnets. ..
Completing tasks in the test network sometimes brings a good profit. One of the last such examples was the airdrop from Aptos, in which for mint free NFT in the test network, its participants received 150 APT, which is approximately equal to $1200. By the way, the activity in this test network has not ended yet, since only 3% of the 51% allocated to the community has been spent.
That's very generous of them. I remember I also got 400 UNI upon using them while they were not releasing a token yet.
This is a risky approach though and will cost a transaction fee which is unsure whether they really will give away tokens. But this is a sign of a near bull market because during the time of UNI, its where coins are also retracing back to high support levels.