Today, I'm going to share one a quick-'n'-easy two hit combo with Street Fighter's Guile.
First, you're going to want to hold Back on the controller to charge for the Sonic Boom. Then press Forward and Weak punch to throw it.
Keep holding Forward to walk toward your opponent, trailing your projectile, after it hits,
follow it up with a Fierce Punch.
Done right, you'll be able to hit your opponent with both of them for a quick 2-hit combo!
And, if you can back your opponent in the corner he won't slide back so far when the initial hit smacks him, giving him less time to recover and avoid the second hit.
Since this is kind of tough to show the timing in picture form, I've created an animated .gif here(4.5MB) that shows it in action.
Oh, and it also works for Street Fighter 4.