Yes please, I would love to see this happen and become more serious.
Maybe it would be good to learn from past mistakes. Many attempts have either been abandonned, or filled with advertising or are mostly inactive now. A list of remaining survivors is shown below.
IMO, such projects need a lot of human time to add/update/remove shops constantly. And thus, a team is probably needed to work together on this to do something nice and to prevent one member to stop the whole project if he/she becomes unavailable for any reason.
It might also be good to contact existing other projects to work with them, or to learn from them. And also, to import/review their existing database.
That said, I don't think this project needs to be decentralized by itself. If someone comes with a brilliant P2P system and prooves that it work in practise, than fine. But meanwhile, probably that any usual way to do it can work. The real matter is probably to put long term efforts and time on it I think.
https://www.spendbitcoins.com/places/http://btcmerchants.com/https://en.bitcoin.it/wiki/Tradehttps://en.bitcoin.it/wiki/Real_world_shopshttp://bitcoinnavigator.com/http://bitcoin.travel/https://www.bitcoinlocator.com/homehttp://www.bitcoinmap.com/