Two entirely unrelated questions

Does anybody have a comprehensive list of USB-interfaced SDR devices out
there that work roughly in the
same spirit as the USRP (even if there aren’t plug-ins for Gnu Radio).
In my other life as
Principal Investigator for the Shirleys Bay Radio Astronomy
Consortium, I managed to get a free donation of
a pair of Ranger 2101 USB extender devices, which I’ve promised to
evaluated for SDR/Radio Astronomy
purposes, and do a little write-up for the manufacturer (ICRON).

On an entirely (mostly) unrelated note, what is the best way to setup a
timer-interrupt in Gnu Radio with
granularity of finer than 1 second, without causing any baffage to
other parts of the signal processing