I'm loving the PiHole and there's one feature that I could think of that I think would be generally useful - especially for those with kids.
There are lots of reports of school kid's results suffering because of addiction to Social Media sites or with online gaming.
The ability to have a second set of blacklist rules that can be implemented on a schedule so to make sure all LAN traffic to/from those sites are gracefully blocked.
I'm sure some routers could do this, but the one we have (VirginMedia Hub3) isn't that smart.
This would help enforce an online curfew where occupants can have full access and at a set time those selected sites will no longer be available.
e.g. At 9pm they can finish watching their YouTube video, but then that's it until 4pm next day (or midday on weekends)