Not the Biggest Bang

But a pretty darned big one, nevertheless. New Scientist has an excellent image gallery illustrating the results of a supercomputer simulation of a type 1a supernova. The blast itself would take about five seconds, but would release the equivalent of 10^27 10-megaton hydrogen bombs.
Now, according to Google the "mass of Earth = 5.9742 × 10^24 kilograms," or 1.3578 × 10^15 megatons (converted to english units). So if you took 7.3649 × 10^11 earth masses (that's 700 billion plus earth masses, not volumes) of dynamite, wired it all to detonate within a five-second window, and set if off, it would yield roughly the same amount of energy as one of these firecrackers.

So again, not the biggest bang, but I feel much safer knowing the above example is confined to a supercomputer and images.