Someone passed along this link to me, and I think it is brilliant!
The University at Buffalo has some digital dissections on their website, labeled and unlabeled. Here is the grasshopper:
They have a variety of vertebrates and invertebrates, all very well done. Each includes internal anatomy as well. You learn the most by doing dissections yourself, but if you need a refresher (or just want to see the inside of a squid), check it out!