I'd like to know if there are any good online books, lecture notes, videos, tutorials, or similar that are free to the public (on differential equations). Suggestions are welcome!
Paul's online notes has a section on Differential equations:
I have not personally read them, but the rest of his notes are helpful and easy to read.
well this one gives you a very huge collection to choose from
It requires you to be a registered member.
You could try my notes, which include ode and pde. There are also applets on my web page.