Since Knoxxy brought it up lets deal with the 'Thieving Disciples' theory.
First of all, let's note that the tomb was sealed and guarded. Guarded by Roman soldiers no less, and history tells us a little bit about that.
Firstly, if a Roman seal was broken, it meant automatic crucifixion upside down for those who did it.
Secondly, Josh McDowell notes that Justin in his Digest 49.16 lists eighteen offenses for which a guard unit could be put to death. These included falling asleep or leaving one’s position unguarded.
These would remove motivation for the Guards to be lax or to run from oncoming disciples. Especially considering that the disciples were a bunch of fishermen, tax collectors etc. and the Roman army was quite formidable.
I'll cite a couple of scholars who have something to say on this issue:
J.N.D. Anderson, former dean of the faculty of law and director of the Institute of Advanced Legal Studies at the University of London, regarding the idea of the disciples robbing the body: “This would run totally contrary to all we know of them: their ethical teaching, the quality of their lives, their steadfastness in suffering and persecution. Nor would it begin to explain their dramatic transformation from dejected and dispirited escapists into witnesses whom no opposition could muzzle.”
He brings up a few points. Not in order: The nature of the opposition they would face was formidable and makes such a suggestion unlikely. Had they been able to beat the Romans then the Romans would have learned of it as well as the Jewish leaders and they would have made sure the theft was known about all over Jerusalem. They would also probably have launched an investigation to retrieve the body, and parade it through town.
What we know of who the disciples became - exceptionally honest, moral and trustworthy - does not fit the profile of someone who founds it all on a theft and a lie.
What we know of what happened to them - giving up profitable professions (eg. tax collectors), persecution, physical, financial, emotional suffering, brutal torture and death - does not fit the idea that the disciples were living a lie.
The behaviour of the disciples before this incident shows them to be entirely different people to brave/daring thieves.
Overall, the whole idea of theft does not fit the situation nor the people.