Last month I entered Unlocking the Potential of XRP Ledger with a proof of concept XRP-only Coil replacement, XRPLoop. It's very, very much only a proof of concept, but I thought some folk here might be interested. I think it could be deployable in a decentralised way, so multiple people could run an instance of it (thinking about things like deploying to Functions as a Service platforms...).
Appreciate it's not interledger, but it does allow for something approximating web monetisation.
Again, it's definitely not code you'd want to run in anything like production, and there's a fair bit of work needed to get to that, but if people here are interested in collaborating that'd be very cool.