avocado> db.geo.ensureGeoIndex("loc");
162534834

avocado> for (i = -90;  i <= 90;  i += 10) 
.......>   for (j = -180; j <= 180; j += 10)
.......>     db.geo.save({ name : "Name" + i + "-" + j,
.......>                   loc: [ i, j ] });

avocado> db.geo.near(0,0).distance();
{ "name" : "0_0",
  "loc" : [ 0, 0 ],
  "_id" : "144958:24840824", "_distance" : 0 }
{ "name" : "0_10",
  "loc" : [ 0, 10 ],
  "_id" : "144958:24906360",
  "_distance" : 1111949.2664455874 }
.
.
{ "name" : "-20_-10",
  "loc" : [ -20, -10 ],
  "_id" : "144958:19925624",
  "_distance" : 2476171.4106209576 }
{ "name" : "-10_-20",
  "loc" : [ -10, -20 ], 
  "_id" : "144958:22284920",
  "_distance" : 2476171.4106209576 }
...more results...