In the interest of showing tactically sound variations on some other takedowns out there, here is a great example from Judo/BJJ black belt Megaton Dias:
Note that it can be done from an upright posture with no close body contact/entanglement – this is much easier to recover from if it fails, or to disengage. You stay on your feet if you want, and going down yourself when all wrapped up with the opponent is not a pre-req of the technique.
If you choose to go down, you can do so without putting your knees into the ground, while getting top control and passing a guard at the same time.
I did a variant of it here – without a keikogi (training uniform) at 1:59 during at an Edged Weapons Overview course by Craig Douglas some time back:
It also works as an ankle pick…