Over on the rtl-sdr.ru blog the programmer of many well used SDR# plugins has released a new one which allows you to have up to two extra VFO’s in SDR# (note in Russian, use Google Translate). In order words this means that you can now listen to up to three signals simultaneously if they are in the same swath of live bandwidth. Previously on Windows only the SDR-Radio V2 software was capable of doing multiple VFO’s.
Listening to multiple frequencies simultaneously has many uses including the ability to now monitor multiple ACARS, AIS, pager and other data frequencies at the same time. However, as of yet it seems that the ability to output to other audio devices such as a virtual audio cable is not yet implemented.