Running this gist against MongoDB 1.8.1 on FreeBSD will crash the server
https://gist.github.com/1071926

Message is:
Fri Jul 8 09:58:29 Invalid access at address: 0x801fffffa

Fri Jul 8 09:58:29 Got signal: 11 (Segmentation fault: 11).

Fri Jul 8 09:58:29 Backtrace:

Fri Jul 8 09:58:29 Invalid access at address: 0x801b1c813

Fri Jul 8 09:58:29 Got signal: 10 (Bus error: 10).

Fri Jul 8 09:58:29 Backtrace:

Repro:
Install node.js
Install npm
npm install mongoose
node crashMongo.js

Expected:
Bad query (because of the blank id)

Observed:
Server crashes

My other test environment is MongoDB 1.6.5 on Linux, and it does not crash

The driver is probably doing something incorrect, but I would expect the server to be robust against ill-formed queries.