Bioninja - Brent Cornell is the author of the go-to site for students and teachers looking for more detail about syllabus statements. I’ve been teaching DP Biology for almost 20 years now, and I visit this site weekly.
Alex Lee’s Youtube Page - If you prefer videos, Alex Lee’s DP Biology videos are another go-to.
BiologyForLife - Gretel von Bargen runs this site for her DP Biology class but has opened it up for everyone.
Netlogo - Good for simulations
ImageJ - Good for measuring things
LoggerLite - Good enough for DP Biology