On steep take-offs (and any bigger drop/jump, really), the pop at take-off is absolutely necessary, and, as davluri mentioned, you want to try and pop right at the rollover, if it's possible to clear it. A lot of times, I'll also take those types of drops at speed, even if it makes a 12'er into a 20'er (providing the landing is just as steep, much farther out).
Another tip, which you may not be doing, is extending the landing gear right before you touch down. Think about a plane landing - it lands at a tilted-upwards angle. This is what you want your skis to look like. Reach down with the tails of your skis as you land (with your feet angled upwards), and as you impact, you'll rock your weight and tips forward, stopping when your stance is centered and your skis are angled just slightly above the slope. Be careful, though - if you get your weight forward in an aggressive skier stance and/or end up angling your skis with the slope, or deeper, you'll likely go over the handlebars. To make it easier to get your weight centered on impact, avoiding a backseat landing, keep your arms way out front of your body, like a normal skier stance, during your entire time in the air and carry this through the landing.
So basically, you avoid taking a digger by starting the landing with your heels/tails and keeping your tips up, and you avoid getting in the backseat by keeping your arms forward and rocking your weight to centered as you impact (watch out for knee-to-the-face!!!). I've never hit anything huge, but this has worked well for me up to 40' and I do tend to have a cleaner stomp than some others I ski with, with an ability to start a turn almost immediately after landing.
Note that this doesn't work well on bigger drops with skis that have soft tails (S7s... yuck) because the impact will just fold the tail on you, causing a wheelie or hot-tub, rather than working in your favor by rocking the tips forward. You want the tail to punch into the landing. Oh, and keep in mind that the angle between your skis and the slope at the touchdown point should be a constant - meaning for steeper landings, you'll angle your feet less. If you don't, you'll be backseated. I always have a hard time remembering to adjust for this when I ski other areas (like Crested Butte), since a lot of landings at my home mountains tend to be on the flatter side of the spectrum.
DISCLAIMER: This is just what I've noticed over the past few years - I'm not a pro. I do ski with a few though, so maybe I'll have a short discussion next time I ski with one. I'm kind of curious now...
Edited by Brian Lindahl - 3/7/11 at 2:23pm