I liked the one about the electric guitar changing music (and lives) the best...for it certainly did.
Although recent events have reminded me of an "A" speech I gave in Speech class. I told of a serial killer who started just off Africa, then crossed the ocean towards America. As usual alerts were given to be on the lookout, but regardless more people died than any serial killer on record. Law enforcement was quite helpless to stop it. And as with most killers, a name was given. Katrina, for instance, cuz my topic was hurricanes. Although this was almost 4 years ago, it's even more relevant now.
And even though I didn't have the required visual aid (other than the chalk board), my instructor loved my intro so much I still got the "A-".