avocado> db.geo.drop();
true

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.count();
357


avocado> db.geo.within(0, 0, 5 * 1000 * 1000)
{ "name" : "Name0-0", "loc" : [ 0, 0 ], "_id" : "162972:24607900" }
{ "name" : "Name0--10", "loc" : [ 0, -10 ], "_id" : "162972:24542364" }
.
.
{ "name" : "Name-10--20", "loc" : [ -10, -20 ], "_id" : "162972:22051996" }
{ "name" : "Name-20-10", "loc" : [ -20, 10 ], "_id" : "162972:19823772" }
...more results...

avocado> db.geo.near(0,0).count();
69