Heard them again this morning (0640 local time, 1040 UTC) on 107.7 MHz FM. Noted that 107.9 MHz is quieted on my radio, they might be closer to 107.75 MHz or even 107.8 MHz.
They appear to be switching back and forth from relaying the local NOAA Weather Radio station (WXK65 on 162.475 MHz) and playing both pre-recorded programming and what appears to be a live DJ.
There was a translator for a local Class-D religious AM station (WLES on 590 kHz AM) on 107.9 MHz (W300DK) but they recently moved down to 97.7 MHz (W249CI), making 107.9 MHz clear again. The closest legal station in this market is on 107.3 MHz (WBBT-FM), making 107.7 MHz a pretty good choice considering how congested the FM band has become with all the translators and repeaters on the air now. Would-be clear frequencies (for example, 106.9 MHz) are occupied by powerhouse stations just outside the market area - in this case, its WAFX out of Suffolk, VA doing 100,000 watts 980 feet above average terrain, even though they're about 65 miles away from Richmond you can still hear them quite nicely with a halfway decent radio/antenna.
The FM band is pretty busy, even in a medium city sized market like Richmond. I can't imagine what the pirates in the northeast (Boston, NYC, etc.) are dealing with in terms of interference.