Man, there's tons of good stuff in this thread. Just a couple points I might throw in.
First a point on the technique in general. When you chamber for this kick, where your knee points is where your foot will extend to. Thus, your chamber is what adjusts the heighth and aim of your kick.
If your style allows/practices low kicks (which would be a good idea) I actually love the low front kick to the shin or knee. It's good by itself because it hurts and distracts the opponent somewhat with little risk to yourself (so long as you properly pull your foot and toes back) and it's great for set up of other moves. This to a low round house to the leg from either leg of yours. The low front tends to jam up your opponent's movement and mess up their rhythm. This is great for mind games too, as you can mix up actual kicks with feints low after they expect it from you.
Another way to approach the front is sort of an opposite method; the power front kick. For more power, engage your hips more and step into the kick, making a thrusting movement rather than a snapping one. Naturally, protect your toes here and this way is slightly slower and more predictable, so I wouldn't try this higher than the midsection, lest you become vulnerable to takedowns. I don't know about you, but I can front kick hard as hell if I want to, so don't neglect this power move. It's great to tack onto a combo or even just try to land as a standalone or mixup single.