We have seen some passengers get serious hot water or steam burns - quite a risk considering that trick almost never works anyway. (Actually I've never seen it work, on myself or any of my passengers to be honest!) Litigiousness or not, I don't recommend it anymore just because it seems too risky for very little benefit.
The best thing is the prophylactic decongestants...second, the gum trick (or even nursing a bottle of water on descent) - keeps the eustacian tube moving and can keep it from getting blocked up. It's not likely to UN-block it once it is though.
The valsalva maneuver can help with a minor blockage: hold your nose, take a deep breath, close your mouth, and blow. Very gentle but steady pressure. If it's seriously blocked, you may be tempted to blow too hard - and you can damage your tympanic membrane. Another word of caution with this maneuver - if you're seriously dehydrated or have a naturally low heart rate, it may be best to avoid. This technique does something called 'carotid massage' and can lower one's heart rate fairly quickly; in fact, many docs will have their patients do this in an emergent situation if their heart rate is dangerously high.
Ear block is nasty, nasty, nasty....my left ear drum actually perforated on a flight once, years ago, before I ever started flying for a living. It was really one of the worst pains I've experienced - and now I have some permanent hearing loss on that side. Yuck! Take care of your ears!
