On this site, you could ask other people to do you a favor - your friends or the people you don't know. There could be some interesting features and rewarding systems. It will work this way - when someone needs help, they come to the site and get the help from the site's visitors.
You would be able to decide the type of a favor you would need, for example:
Social media help (to follow/like/click something)
Rating some pictures/videos/articles or commenting/thumbs up/star rating
Supporting some causes
Voting on some contest
Helping to do some real-life, common work
Every type of favor will have its specific format and the accomplished favors should be verified and credits given to the people/person who helped/did it. The helper will get some kind of reward for its participation, for example, some credits/discounts etc. This will not be something similar to those marketplaces like fivver/upwork/guru. There, people offer services and are paid for it. This will be a favor-place where people are motivated by helping others, not by earning money.