Blundering your queen away to no clear advantage often causes immediate resignation. In this game I managed to see a line of attack and luckily it worked. After a player is up a queen, it is easy for them to relax mentally and make a mistake or two.

developing his pieces might have been a plan 

well played.nice to see.

That wasn't a blunder!  It was a sac!  It worked well against Black.

Reminds me of this one ...

http://www.chess.com/forum/view/general/my-recent-otb-tournament-game

However I had nothing near a "line of attack" in this one, and was very short of resigning, it was just my opponent who gave me the queen back for no apparent reason :)

That was a nice game, and congrats on pulling it out. I often seem to play better when I'm down.

I wonder, though, if this would have worked had black played "11. ...f6". White would have had to pull back the knight, I think, and I think black could have then turned things around with the material advantage.

 I don't think it is unusual for players to miss opportunities like that when they are tired and assume that the play was sound. It's always a great relief when the opportunity slips away from them.

 I agree that this was not a game with a compelling progression. Driving the knight back would have sapped White's aggression. However, the lesson I take home is that when the advantage shifts there is sometimes a psychological stumble by the player with a decisive advantage. As long as there is material on the board you have a chance.

Why?

That, of course, is for you to find out :-)

Steiner: magnificent conception.  

SPOILER

14:... Qf3! when the Queen is trapped, but it's not...

Yeah, thanks. Another time, assume I'm rated 650 points below you for a reason, 'k?

Thanks, Gambitknight, the mate after 15. gxf3 is awesome, and otherwise, White's losing a key pawn by the look of it.

Queen is trapped

Hey, take it easy. It's kind of a puzzle, so if you at first don't get it I'm going to let someone else try and figure it out instead of just posting the "solution", right?

You are of course correct, black wins a pawn after 0-0 Qxe4, and has all the fun with the initiative on his side and good prospects of winning white's overextended d-pawn as well, in the long run.

I agree. Queen is not trapped. Nf3+!

Nf3? Kf1.