I release most of my fish... I generally keep a stocked kitchen (unusual for a bachelor, I know
) and unless I know all of the meat will be used right away by myself or others I don't see the point in keeping it. Much more of a hassle to fillet it, anyway.
Now, PBs are a different story. I know that when I got my first 40 this year I had no intention of letting it go... It was just a landmark that I strove for, I knew people who were asking for fish for a BBQ, and the cup was going on. It's gotta be the hardest thing in the world for anyone to knowingly release their PB... More power in the world to you if you can do it, however.
I probably won't keep many (if any) 20-30 pounders ever again... They just don't taste as good as a 28" fish. But when (read: if) that 50 comes around, it's probably coming home with me. Donating the fillets to local food banks/ soup kitchens can also be an option with a fish like that.
RF9 raises an interesting point though. What really irks me is all of the pics I see of people holding cows straight up and down with their hands deep in their gills... with a comment that reads 'caught and released'. The damage to the gills and internal organs must be severe, and even with careful resuscitation the chance of that fish surviving have got to be really low. If you treat a fish like that once it's out of the water, you might as well just keep it.