I just ordered the $10 SDR/DVB dongle upthread. I think that with two PCBs stacked you could actually jam this inside a Neo900 with a Mugen cover though it would need a hole for an antenna connector. Glad I bought 3 covers when they were cheap!
Talking about the gqrx missing lib, you shoud add to /etc/ld.so.conf the path "/opt/gnuradio/lib" or create the symbolic links of the gnuradio libs into /usr/lib.
Doing this, gqrx will be able to use the gnuradio libs.
The gqrx GUI doesn't fit into the screen and it seems that the cpu load is to heavy to work seamlessly but wtf it works on N900 !
I also tried multimon-ng, there is no error, I think it works but I have no possibility to test a signal today.
Even if rtl_fm is the only continuous part I'm very lucky
My dongle is a "Terratec ran T-Stick+", not mentioned at the most manuals, but it works with rtl-sdr on N900, raspberry PI, Debian, Win sdr#, ... bought at "Conrad" store (20€, there are cheaper dongles but if you can't wait it's ok)