An app that allows people to ask for favours from their friends and anyone within a certain radius. Could grow into a marketplace for local tasks (doing the shopping, giving advice, menial tasks etc). Any thoughts?
The Buy Nothing Project (started by a couple of friends of mine) is a successful model for this. It's not an app, but a network of Facebook groups.
From their 'About' page: "The Buy Nothing Project began as an experimental hyper-local gift economy on Bainbridge Island, WA; in just 8 months, it has become a social movement, growing to over 25,000 members in 150 groups, in 4 countries. Our local groups form gift economies that are complementary and parallel to local cash economies; whether people join because they’d like to quickly get rid of things that are cluttering their lives, or simply to save money by getting things for free, they quickly discover that our groups are not just another free recycling platform"
If I understand you correctly, this is for buying gifts for others and getting the same in return. I think the OP meant doing something for someone else, e.g. getting something from a store you're going to anyway, but being refunded.
I wouldn't be as inclined to gift something to a stranger as much as I'd be to grab something along for someone nearby. I don't need to be reimbursed for the effort, but I also don't want to loose money on it.
Buy Nothing Project (BNP) isn't about "gifts" in that sense. Here, the "gift economy" is "a mode of exchange where valuables are not sold, but rather given without an explicit agreement for immediate or future rewards".
An aim of BNP is to build a hyper-local community where people give and receive goods and services with no money or bartering involved. You get to know the people involved in your group, because only people living within a certain area are allowed to be in the group. And yes, groups do indeed have people picking up things from stores for each other, or giving them rides, on occasion. Some groups including informal lending libraries, where you can borrow tools, equipment, household items an no charge.
Around here on Bainbridge Island, you often see tables on porches for BNB'ers (Buy Nothing Bainbridge members) to pick up stuff. The things (a garlic press; a pair of pants; a lawnmower) will have been listed on the group's FB page, probably with a photo, then there'll have been a few people saying they'd love to have it. Sometimes things go first-come, first-served; other times people get randomly selected.
From their 'About' page: "The Buy Nothing Project began as an experimental hyper-local gift economy on Bainbridge Island, WA; in just 8 months, it has become a social movement, growing to over 25,000 members in 150 groups, in 4 countries. Our local groups form gift economies that are complementary and parallel to local cash economies; whether people join because they’d like to quickly get rid of things that are cluttering their lives, or simply to save money by getting things for free, they quickly discover that our groups are not just another free recycling platform"
http://buynothingproject.org/