I have a "room for improvement" item regarding mongoimport error messaging.
There was an error in the JSON file that threw the error shown below. EX:

{ "_id" : "10005", "city" : "New York",

We need a way to know the line content and the
line number of the data where the error occurred as this current format
doesn't provide that. Maybe its buried in the Hex output. If I have a zillion lines of JSON, I need to know where to go to fix the data. Shouldn't be that hard to say:
ERROR at line 2
ERROR CONTENT: { "_id" : "10005", "city" : "New York",

Fri Oct 21 07:56:03 Assertion: 10340:Failure parsing JSON string
near: ,
0x5847a2 0x528af4 0xa95ba3 0xa97e53 0xa8e98d 0xa92922 0x7f62007de30d
0x4fd0c9
mongoimport(_ZN5mongo11msgassertedEiPKc+0x112) [0x5847a2]
mongoimport(_ZN5mongo8fromjsonEPKcPi+0x444) [0x528af4]
mongoimport(_ZN6Import8parseRowEPSiRN5mongo7BSONObjERi+0x8b3)
[0xa95ba3]
mongoimport(_ZN6Import3runEv+0x16e3) [0xa97e53]
mongoimport(_ZN5mongo4Tool4mainEiPPc+0x169d) [0xa8e98d]
mongoimport(main+0x32) [0xa92922]
/lib/x86_64-linux-gnu/libc.so.6(__libc_start_main+0xed)
[0x7f62007de30d]
mongoimport(__gxx_personality_v0+0x3e1) [0x4fd0c9]
exception:Failure parsing JSON string near: ,