Cforst,
If you're flying with a cold, there's not a lot you can do. The only relief you're likely to find, other than what you've already mentioned, is the valsalva maneuver. This involves holding your breath, plugging your nose, and attempting to exhale through your nose. This is more geared toward your sinus cavities than your ears.
As you climb, if your sinuses and eustation tubes are clogged, air expands inside your ear and your sinus cavities. This air is forced out as you experience an increase in cabin pressure altitude. However, when you attempt to come back down, you're faced with a substantial pressure difference, with the lower pressure now in your ear and sinus. This can be quite painful, and in some cases, can result in a rupture of your sinus lining. When I was a teenager, I ended up going to the emergency room after one such experience.
You can sometimes clear your ears, but often not if the blockage is very bad.
I'd encourage you not to fly if you know you're sick (which isn't always the case; you can feel well, especially if taking some medication), but still experience a blockage. That's the best method. If you do find yourself going somewhere on short notice with some sinus irritation (cold, hay fever, whatever), for whatever this is worth, take some sudafed in advance, suck on some fisherman's friend, chew gum, pop your ears as much as you can and as frequently as you can, and hope for slow, small changes in cabin pressure.
Perform the Valsalva maneuver frequently instead of a few times during the descent. It's far easier to maintain equilibrium if you keep doing it every thirty seconds, as opposed to every few minutes. You have less differential to relieve. I hope some of that helps.
