This collection of online textbooks and science literature is an absolute gold mine for students and researchers alike. If your protein of interst turns out to be involved in patterning you can look up Wnt signalling in Developmental Biology. If you need to understand the basics of DNA repair you can see a good overview in Molecular Cell Biology. If you're giving a talk and need a pretty diagram to show how DNA is arranged into chromatin you can search the entire library until you find your favorite (which you will of course reference in your talk). This collection is often forgotten by scientists because we tend to look in journal articles for our most up to date information. But when you need a refresher on organic chemistry or bacterial nomenclature, sometimes the books are the place to go.