The people above all noded how to kill vampires in traditional folklore. However, I feel that cultures are being somewhat unfairly represented, as culture is more than just folklore. Ergo, I decided to, using many references to vampire stories, modern or otherwise, to contribure to this writeup.
Now, noting many cultures, vampires seem to be warded off by holy symbols/relics/miscellany. What I want to know is, what are the vampires so afraid of? Could it be that vampires are burned by holiness as well as by light? It seems quite possible, as vampires usually are put in a rather, err, dark light.
If the above is true, that vampires are truly unholy, then the really inventive could use a quicker method. First, when the vampire comes toward you, you must ensure that you have the proper protection, namely a crucifix, as it would suck (ha, ha... ah.) to be devoid completely of blood by not protecting your sensitive regions, namely your jugular. Now, the vampire, as I said, is coming to you. He suddenly recoils, seeing the holy symbol about your neck. Now, as to avoid being killed a more traditional way (like swords or guns), you must act fast.
Pull out the Bible you had stashed all along, and swing it at the vampire quickly. It should dissolve into blood, flame, and dust as its torso is rended from its lower half.
There is a second way that I would also like to postulate. Vampires, as many people know, are warded away by garlic. Now using a fantastic leap of logic, I would like to theorize that garlic puts vampires in a weakened state, like Superman to kryptonite.
The first step would be hard to pull off. First, you must somehow surround the vampire with garlic. Then (the next step is far easier), shoot him in the heart (with a silver bullet, to be stupid, as werewolves are killed that way, to be ironic, but most of all, to be poetic). Hopefully, he should die mortally, but as this has not been tested, it could be risky.
Congratulations. You killed a vampire!