teacher demo of lighting a Bunsen with the spark from your finger after you've charge d yourself up on a Van Der Graff. If you've never tried it it's rather fun (doesn't work 100% of the time for me - depends on the charge you can get)
have always been a big fan of the van de graaff generator, but was introduced to a cool demo this year - aluminium cake cases piled on the top fly everywhere when switched on! Cutout paper tissue 'ghost' shapes also work well for this.