Hi there! There are lots of them.
Most of the ICO's has a bounty campaign as a way to advertise their platform and increase their community.
Find bellow some ICO's rating websites where you can find  great Bounty campaigns:

ICOBench   https://icobench.com/
ICO Champs   https://www.icochamps.com/rated-ico-list
ICO Marks   https://icomarks.com/icos
ICO Rating   https://icorating.com/
Crush Crypto   https://crushcrypto.com/ico-review/
Coin Schedule   https://www.coinschedule.com/
ICO Gens   https://icogens.com/
Crypto Rated   https://cryptorated.com/ico-reviews/
ICO Drops   https://icodrops.com/
ICO Alert   https://www.icoalert.com/en/
ICO Watch List   https://icowatchlist.com/
Coin Gecko   https://www.coingecko.com/en
The Tokener   https://thetokener.com/
Top ICO List   https://topicolist.com/
Coin Market Plus   https://www.coinmarketplus.com/
ICO Creed   http://icocreed.com/
List ICO   https://www.listico.io/