Is there a network or consortium for small licensed money transmitters in the US?

Not really. There was an effort by David Landman to create the NMTA, but that has now been morphed into MSBA (Money Services Business Association). Their website can be found here: Money Services Business Association

NMTA (National Money Transmitters Association) was a great newsletter that David put out, to join the industry, and the newsletter is still there (just with a different name), but for all purposes, MSBA is the de facto association to join.

From a license alliance point of view, there is none. I did start one (and still have one), but that is more from a point of view of obtaining money transmitter licenses by leveraging the licenses of others: Money Transfer Alliance Program - Faisal Khan