None yet - i'm just spit balling
and yes I've thought a fair bit about a way around the whole security thing. The last thing the big Telcos want is for it's clients to begin using all the data they pay for.
I don't think it could be on an individual P2P exchange
If we had a central pool where we could all dump our excess data, via smart contract of course, and receive "This Token" in exchange. Let's say 100 tokens = 1gigabite of data
Then people could sell Their tokens received to an interested buyer for X ( whatever the market dictates)
When the buyer receives his purchased tokens he could then redeem them in the central pool for the data amount.
Again I'm just thinking outloud here, but it is possible i believe.
Plz send critiques and comments and anything that comes to your mind here post away.
B