The other thing one might discuss is: When shouldn't I resign?

I often resign instantly after a blunder because I feel that i messed it up and my opponent will win easily. But sometimes I realize later, that I still had good drawing chances. One game I wanted to resign against a lower rated opponent because I made an opening blunder. But I could resist these tempting feelings and won the game.

I AGREE-- TO PREMATURLY RESIGN IS A COPOUT

NEVER resign when your opponent is up by material and you're left with just 2-3 pawns or so. Remember, there's always hope for stalemate! :)

Yay I got one!
http://www.chess.com/livechess/game.html?id=298026812  

Like a pro! Very nice!

the frrst game should have ended 30 moves less...

the person was just playing a joke on you..

-Apsd1109

In a more serious blitz game, I played poorly and ended up in a lost position. I was very close to resigning, but I got curious to see if my opponent could properly finish me off. Much to my shock, he completely blundered the win into a loss! 

The game is a double of example of when to resign and when not to. In my case, not resigning was the right call. In my opponent's case, he should have resigned after I cleared his pawns.

@FirebrandX: In which move did you want to resign?

Well I knew I was in serious trouble by 27.Ne5+ since his two extra central pawns were far better than my exchange advantage, but the point where I was very tempted to hit the resign button was after 41.Ne5. I was absolutely lost by that point, but I decided to wait until my opponent forced a successful queened pawn and resign then. That was when my opponent somehow managed to play exactly the wrong moves to lose a totally won endgame position.

...

@Firebrandx: Right, you are lost there. In a longer time control he would probably manage to find the way to queen, but his lack of endgame technique proved to be fatal under time pressure. So you might well resign in move 41  if he has plenty of time (and probably will use it to find good moves) or if you know he has a decent endgame technique. Against unkown in a blitz game it's fine to continue for a while. 
In blitz without increment I often play it out in lost positions when both sides haven't much time. Just because I can still hope my opponent will loose on time. In blitz without increment I myself have lost so many games with very good position on time because my opponent won't resign. So I can't blame somebody for not resigning in a blitz game.

Telling someone to learn how and when to resign is very poor and useless advice.  There's absolutely no greater benefit in resigning early than there is in playing it out, even if it appears that you have no chance.  The manner in which you lose makes no difference what-so-ever to your score. There were times when grandmasters told Bobby Fishcer that he should resign to retain his pride, only to witness Fischer go on and win the game.  

Did you even bother to look at the example games in this thread?