There seems to be a growing trend towards considering diets that are primarily vegetarian. There are a number of issues raised in this excellent NY Times article (http://www.nytimes.com/2008/01/27/weekinreview/27bittman.html
) but to me it breaks down like this:
1) Raising cattle, pigs and chickens is hard on the environment (space, waste, feed).
2) Mass producing livestock requires sacrifices in quality of the meat (antibiotics, cheap feed).
3) Mass producing livestock requires sacrifices in the quality of the animals' lives.
I'm unlikely to ever give up eating meat entirely. I believe that a great steak or roasted chicken is one of the cornerstone joys of humanity. But I could meat once a week (and sometimes do) without a major modification to my diet. Meat will inevitably have to become more expensive and the standards higher in raising livestock.
The reality is that these same standards will have to apply to seafood too. We're badly overfishing the seas.
This article about my favorite football player, Mr. Tony Gonzales, is very inspirational too. His diet is too extreme for my taste, but I respect what he has accomplished: http://online.wsj.com/article/SB120122116182915297.html