For Gundrabur -- IRC 2013/09/02

gistfile1.js

r.db('test').table('test').filter({username:"Michel"})
  .groupBy('origin', r.count)
  .filter( r.row("reduction").gt(1))
  .map(function(result) {
    return r.db('test').table('test')
      .filter({username:"Michel", origin: result("group")("origin")})
      .coerceTo('array')
  })

Revision to return just the origins

r.db('test').table('test').filter({username:"Michel"})
  .groupBy('origin', r.count)
  .map(function(result) {
    return result("group")("origin")
  })

More chaining

r.db('test').table('test').filter({username:"Michel"})
  .groupBy('origin', r.count)
  .map(function(result) {
    return result("group")("origin")
  })
  .map( function(origin) {
    return r.db("test").table("documents").get(origin)
  })