Perseus Vase Catalog/Herakles
Here you will find a nice selection of vases from Perseus in which the hero Heracles figures. Read the vase descriptions and click on the images of those which interest you. (Note: Not all of the images may be available to you.)
Metopes from Olympia
AERIA—Antikensammlung Erlangen Internet Archive contains collections of ancient art in various categories. Here you will find the metopes from the temple of Zeus at Olympia which depict the Labors of Hercules. And you might learn a little German!
Ercole e Caco
Thais—1200 Years of Italian Sculpture. Scroll down to Michelangelo Buonarotti and click the thumbnail of his statue of Hercules subduing Cacus.
Read section 3 of Frazier’s Summary of Apollodorus handbook of mythology dealing with Heracles. At any point you can click on the reference number in the text to take you to the fuller treatment in Apollodorus himself.