I was checking Twitter while I waited for a PCR to finish and I found these nice cartoons by Ed Himelblau at the Promega site (you can follow Promega here). I selected a few, but you should check them all out!
Alejandro Montenegro-Montero is a grad student in the Molecular Genetics Program at Pontificia Universidad Católica de Chile. He is the editor of Molbio Research Highlights. You can contact him at "aemonten (at) gmail.com"