I can think of just a few in particular that should really work for you.
1. Cowgirl (you on top). This should work regardless of the size of either of you (unless the girl is really big and the guy's really little, as said before). This gives you complete control and him the chance to relax and enjoy the view. And if you do it reverse (you facing his feet) you have lots of extra space around your pussy to use a vibrator (if the guys got a bit of a gut, using a clitoral vibe can be a bit tough).
2. Standing. The position works well with a shorter woman, when done right. Try standing up against a wall with something nearby to put a foot on. With him in front of you, have him lift you up and push you against the wall (using the stool/chair/whatever to help support you if you need it). Get high enough for him to enter you and wrap you leg/legs around him. Then go for it.
This takes some balance from you and some strength from him, but is great for those passionate, desperate love-making sessions.
3. You sitting, him standing. This is simply when you sit on a surface that's at a good height for him to enter you without having to bend his knees or stand on his toes too badly. Kitchen counters, dining room tables, and washing machines should all work pretty well.
It's good because height shouldn't really matter, and if he's a little too tall, he should be able to bend enough to enter you without too much trouble.
Doggy Style might work, but it depends on how different the height is as far as your legs go. It can be tough when your legs, thighs especially, are too close or too different in height. At least, that's how I see it.
I'm sure you're well acquainted with missionary, but if you have trouble with it because of height, try with your legs over his shoulders, or both legs and hips over to one side. Having your legs over the side of the bed might work as well.
Good luck!
ps. If you don't mind, I'd like to post your question (anonymously) and my answer on my blog. Please let me know if you object.
<3
~Sin