You can find additional experiments at Candy Experiments, as well as some you've seen here (what can I say, great minds think alike!).
In addition to several new experiment ideas, Loralee also has made instructional printables available would be great for setting up lab stations or party stations (and I LOVE the idea of handing them out along with the Halloween candy) and tips for running a successful candy experiment party.
Have fun exploring, and then playing!