I have been making lots of food requiring onions lately, which isn't too out of the norm- but I thought I'd share with you a technique to make dicing them as easy as possible!
I originally learned how to do this at Tammy's Recipes, and what a great timesaver and tear-reducer it's been!
First, slice the ends off your onion and remove the outer skin.
Turn the onion so the middle (where you cut it in half) is face-down on the cutting board (like the onion half in the bottom of the pic below).
Slice the onion lengthwise while holding the onion to keep its shape.
Turn the onion 90 degrees so the slices you just made are going the other direction.
Dice your onion while holding your knife at an angle while going from one side of the onion to the other, changing the angle so the knife is more parallel with the cutting board (but never totally parallel).
You don't even really have to do this if you don't mind if your onion "cubes" aren't perfectly uniform. You can see the knife angle I'm talking about in the pic below.
Cut closer together for a smaller dice, further apart for a coarse dice.
Hopefully there will be less tears with this faster onion-dicing method. I also read if you light a small candle in the vicinity of where you are chopping it will burn up the vapors that cause the crying. I have done it sometimes, and I think it works- but I'm not totally sure if it's real or all in my head. Let me know if it works if you try it.