Sensei taught me a way of sweeping that is in reality a low round kick to the leg you intend to sweep, connecting with the instep/ shin (SOME conditioning is useful, but since you're striking the side of the opponent's leg, not strictly necessary if you're willing to deal with some pain occasionally, if you don't get it quite right). Once you've struck, and hopefully displaced the leg, continue through by hooking it with your instep. Pull your leg in, as you do so, rotate your foot so that the arc of your foot is now in contact with the opponents leg, as in a regular sweep. Continue sweeping from the now familiar position.
My favorite combo, assuming you're right handed and stand with your left foot forward, and the opponent is also standing this way: Lunge in with left foot, right foot pushing, execute a jab to the face with your left. If the opponent recoils/ withdraws, leave the left foot where it is, VERY QUICKLY bring the right foot in halfway to meet the left. Push off with the right foot and lunge with the left. This time strike simultaneously (As you lunge) with a right reverse punch to the body (The opponent's guard will be high due to your jab to the face). If he recoils/ withdraws again, sweep his front leg with you rear (Right) leg. As you are landing from the sweep, push of with your left leg (Now to the rear, you swept with your right one, remember?), lunge in with your right leg and simultaneously hit him in the face with a left hand reverse punch (His guard should have gone low from your previous punch, plus people drop their hands when unbalalanced by a sweep).
[This message has been edited by MAGon (edited 08-11-2003).]