What do dry ice, heroin, and trampolines have in common?
They don't just make for interesting Halloween parties. Check out this pretty comprehensive list of genericized (and protected) trade names.
And here's the Wiki entry for genericide, which is also fairly accurate. Note, though, that the list of examples doesn't distinguish which brands are still protected (e.g., Google, Kleenex, Jacuzzi), and which have lost their protection (e.g., aspirin, zipper).
I can't find confirmation online about this, but I heard once that the word "zonk" (as in, "I totally zonked out for three days after finals were over!") was originally the name of a narcotic-based patent medicine at the turn of the 20th century.