Transferring ownership of an asset is easy. Amazon do it every time you click the Buy button. Trading the time of people, or resources, for precise amounts of time in exact geographic locations is much more complex.
Assume you're willing to rent out your caravan for 2 days. Any website brokering a deal for you must handle issues including: constantly changing availability, personalised contactability, varying reliability, real-time multi-parameter price construction, buyer/seller acceptability to each other, resolution of failed transactions, underwriting of transactions, payment escrow and transfer, tax implications and insurance of assets. That’s the starting point. If it’s to be truly useful, it also needs to offer futuristic facilities like aggregated investment in targeted seller development. We’ll explain in the other facilities section.
Think of e-commerce in terms of a spectrum of mechanisms for trade. No one mechanism is right for every kind of transaction. You don’t auction groceries, it would be unnecessarily time consuming; and price discovery, a key benefit of auctions, isn’t an issue. Here’s an overview of existing trading mechanisms in online markets.

NEMs demands a new mechanism. There is technology that enables very precise localised time-based trades. It’s called UltraFlexi. Developed over 14 years in British think tanks and technology companies, a version is currently allowing people across the UK to sell their spare time to local employers. The scheme is called Slives-of-Time Working.