According to this Wired blog post, Delta is planning some new coach seating that may actually not be horribly uncomfortable. Here's a snip:
Tall, sleepy air travelers, rejoice! The Cozy Suite manages to stretch legroom by two inches while fitting airplane seats into the standard economy class 32" pitch. It does this by offsetting the seats diagonally: they still point forward, but each chair sits behind its neighbor. This staggered arrangement also means that there is space to put in a padded side section to lean against and get some proper mile-high shuteye.
We may have to wait a bit, but supposedly relief will be coming to Delta 767 and 777 passengers by 2010.