Premature Resignations

It really sucks when you resign a game only to later realize you could have drawn or even won.  This game was an OTB game I played against an around 1500 player.  The game featured mutual mistakes and in the end I resigned because I thought I had lost a queen, when in fact, I could have won.  My opponent pointed this out as soon as I tipped over my king.  I was furious at myself for weeks because of this game.  Any thoughts?  Has anything similar ever happened to you?

All in all, one my worst blunders.  However, let this be a lesson to look thoroughly before resign and only do so if you have no winning chances.  It's too bad that I had to learn this the hard way though.