Promoting pawns: but not to a queen

So, under what circumstances would you promote your pawns to a piece other than the mighty queen.  If you could upload diagrams of some of your games where this occured, then even better.
I am thinking of one where I used knights several times, but it will take me a while to find...

Knight is simple, it's just when you need that particular square covered. When you promote to rook or bishop, it's nearly always it's to avoid stalemate. Take a look at this puzzle. 

https://www.chess.com/blog/Robert_New_Alekhine/puzzle-of-the-day-february-18th-2016

You either do that if you can use the Knight's special move ability or to avoid stale mate. See the beautiful trap from Albin's counter gambit. You should try to play this very line as black at least once before you die.
 

7. Ke2 fxg1=N+! (see diagram)

Underpromotion is the key to the trap. (If instead 7...fxg1=Q, then 8.Qxd8+ Kxd8 9.Rxg1 is okay for White.) Now 8.Rxg1 Bg4+ skewers White's queen, so the king must move again.

8. Ke1 Qh4+ 9. Kd2

The alternative, 9.g3, loses the h1-rook to the fork 9...Qe4+.

9... Nc6

White is hopelessly lost. After 10.Bc3, 10...Bg4 followed by 11...0-0-0+ is crushing.

I will sometimes sub promote if I'm serious material up and show a little contempt for my opponent playing on.

In an OTB game I sub promoted to a bishop for the sheer hell of it once because I couldn't avoid mate in a couple of moves

The usual sub promotion is to a knight to gain time with a check/fork perhaps...

There is a famous discussion about the game Fenton v Potter.  A position occurred where sub promoting to a rook in one variation avoided stalemate...

http://www.chessgames.com/perl/chessgame?gid=1607862

Well... One example is when you want to

Confuse your opponent

Ah yes, logozar!

An excellent example logozar! Whenever you see the opponent's King and Queen that close to each other, you should consider underpromoting to a Knight so that you can fork those two pieces.

Riigghhhhtttt.  That's given us all something to think about

Gotta have my queen!

What... you don't believe me? I can prove that promoting to the queen is basically losing...

Here:

thank you very much

Here's a position where I promoted to a rook.  Promoting to a queen would have been stalemate

I've seen people get multiple queens (mostly out of spite because their opponent won't resign), but multiple knights is a new one.  Didn't even have to include the king in the mate.

nice...

https://www.chess.com/blog/Harish73/finally-opponent-was-trapped

logozar's example is examplary!

As is Pfren's. They're both equally good.

If my opponent is a stubborn nonresigner I sometimes under promote so I and mate him with Bishop and Knight.

For a practice for beginner he can always promote to a rook to mate 

yep