That's a great idea @timcliff!
The great benefit here would seem to be that people can use their smaller amounts of Steem/SBD inside the community, without having to go to fiat via an external exchange, which inevitably costs.
I could easily see this becoming a two-way flow, with "SteemEconomy" serving both as a directory, as well as a portal to help potential merchants by showing the the available options like @steembay, @steemshop, @peerhub and others. Although that might be outside the scope of what you had in mind, I don't know.
=^..^=