Hi Barrett,
The khanjar is more or less interchangeable with jambiya, depending where you go. I understand jambiya is specifically Yemeni (or is it Omani?) while khanjar applies to the rest of the muslim world and India. It is a curved dagger, invariably double edged. They range from small to quite large ones like the Arabian Wahabyte jambiya. The kindjal on the other hand is usually straight as Wolviex said, but there are examples of curved ones. Actually, depending on where you are, some khanjar/jambiya really border the line to being kindjal/qama IMHO. I've seen some Ottoman examples like this.
Use the search function on this forum, you'll find a treasure trove of info on virtually any weapon you can think of. I also recommend looking at
www.oriental-arms.com, as they have a massive database of oriental and other weapons with good pictures and descriptions.
All the best,
Emanuel