In Banded tournaments, players whose ratings have risen 150 points over the upper band would not move on to the next round. The second place player in that section would move on instead. Of course, there's still the issue of sandbagging but that's not the problem that this solution is addressing.
In my own situation, I entered a bunch of Banded tourneys when I first joined and didn't really understand how tourneys worked. I really don't belong in these sections now, but I don't see a graceful way of exiting besides resigning games, which I'm not comfortable doing. There are many others in this same situation (I'm playing some of them! =)
I'd think that this would be easy to code but I'm no expert. This also would make Banded tournaments a lot more popular. 150 points seems right to me, maybe it'd be worth experimenting with 100 or 200 points instead.
What do other folks think?