:-)
Of course, it's a tough hill to climb - the folks making cases no doubt have already patented the obvious (and many not so obvious) things... Accelerometers were important in things with hard drives - dunno if they'll help in protection for things with Flash RAM these days. Maybe if you tied an accelerometer into a phase change material that would go from hard to soft when it senses it is falling. ;-)
The Otterbox Defender claims to address issues like that and have multiple layers to cover the various functional needs. But when you don't need those various protections (99% of the time), it gets in the way.
http://www.otterbox....cgid=ipad-2-cases - $90 for the iPad v2 version (they don't sell the v1 version any more). :-/
If one is willing to spend $90 for a case, one probably has AppleCare+ for it as well ($99 ($90 at Amazon) + $50 for each incident (up to 2) for 2 years total coverage). AC+ might be a better value than the case. And there's things like SquareTrade with roughly similar damage coverage (maybe?) for an additional year for a similar price (but no deductible).
FWIW.
Cheers,
Scott.