I find this site slightly creepy (thanks to my aversion to bugs), but it is so informative that there was no way I was going to skip sharing it with you.
The articles are setup blog style, you just scroll down to read the most recent articles. As you scroll down notice that on the right side of the page, there is a section labeled Categories. If you click into any of these sections under categories you will find all the articles related to that topic and more often than not, information on that kind of bite and images of what the bites look like.
The Categories are: Ant Bites, Bed Bugs, Black Widow Spider Bites, Chiggers, Flea Bites, Midge Bites, Mites, Mosquito Bites, Pirate Bug Bites, Spider Bites, Wasp and Bee Stings.
At any point during your visit to the site you can click the Home tab at the top to be returned to the main page. I thought that this site was a good resource for learning about bug bites and that you could even use it to possibly help identify bug bites!