I'll try and make it realistic from the point of view of including many tasks that people generally want to do.
So I'll have it serve static files, read and write to a database, read a local config, cache stuff in memory, do something on a scheduled task basis, render templates.
Anything else anyone would like to see?
Not sure what I'll make that will require all of that, and I would like to keep it enough of a stub that people could rip out the example and quickly butcher it into whatever they wanted to prototype.
Maybe a code snippets site. I'm off out for the day, my first day off in 60 days, so I'll look at this tomorrow.
I'm thinking a good default would use the default templates (as they are good), memcached, PostgreSQL, have a config file in /etc (because no-one should be hard-coding their app, even if it's a quick thing) and I'll make some excuse to include the scheduled tasks as there is always an edge case need for them. I won't try and solve user login, I'll just use Persona.
It will be basic, but have a lot of simple components that people can delete out or extend depending on what they want to do.
Once I've put it up, I'll accept pull requests... I'm sure there's enough people with small reqs that it could be knocked into shape enough to show how to do most things.
I use a Rails-ish directory structure {controllers,models,helpers,server,views} and can be knocking out the first skeleton pages and APIs in minutes.
I don't think Go needs a framework to be a really good fast web app language/environment.
If anyone is interested in a sample app I might knock one up just so that people can clone it and get started. There wouldn't be much to it, as I'm consumed by other work, but maybe people want such an example.