Well, I suppose if you were lucky enough to have 30 offers then you might be in a slightly different situation and I would love to tell your story on the blog. In my experience, especially in the recent economy, candidates are lucky to have one offer. Those that receive multiple are in great shape, and I have yet to hear of anyone that has trouble with too many offers to respond to.
Again, if that's you or you know someone, I want to interview you to find out how you did it.
Say you have 30 offers on the table. What's to be had by saying "no" to 29 of them instead of just "yes" to 1 and not replying to the rest?
If that 1 drops out you now have 29 pending job offers.
If you "declined" the rest, you now have what pending?