Here's one we've mentioned more than once at our house...
Family Delete Feature:
Set up a number of "Delete Users" and assign "Delete Users" to each recording. The recording will only delete from the hard drive when all users assigned to it have "checked off" on the programs deletion.
For example, My wife and I both love watching Heroes. She works Monday evenings. I usually watch it later Monday night after the kids are asleep, but she doesn't usually watch it until Tuesday afternoon. It would be nice if I could check off "Delete" next to my name when I'm finished watching it, and when she watches it and "checks off" the delete box the system will then, and only then, delete the episode because both users have deleted it.
The other feature I'd like to see is ethernet based networking of DVRs (and non-DVRs if possible). If DVR 1 records a show, allow the other receivers in the house to view it via streaming the show across the network. I read something in another post about smart scheduling like MythTV (if DVR 1 is recording on all inputs, auto-schedule DVR 2 to record the episode), I'd like that too. Since all DVRs would be networked at that point, where the show resides for playback is of no concern.
Kurt