There are lots of groups, channels, sites, threads, pages, and forums that are usually meant for announcing Bounty Campaigns.
You can find plenty of it at
https://bitcointalk.org/index.php?board=52.0
https://bitcointalk.org/index.php?board=238.0
https://t.me/TheBest_Airdrop
https://icorating.com/
https://twitter.com/BountyCamps

And if you are still finding a Bounty campaign where to participate or Invest with I may suggest you to Project Daneel.io. Its an A.I. (Artificial Intelligence) assistant created and develop to help and guide investors in this cryptoworld.
You can check their website at:
https://daneel.io/
BitcoinTalk Forum Bounty Program
Link : https://bitcointalk.org/index.php?topic=2667581.msg27210952#msg27210952
Total allocation of this program: 2'500'000 DAN tokens (2,5%)