This is a resource I cannot keep for myself. The Stacks Project is a massive collaborative effort to create a reference for algebra and algebraic geometry. Ever wanted to read a 2236 page document on sheaves, schemes and much more? Now is your chance!
An interesting feature is that it's possible to create dependency graphs from the project, visualizing what is necessary for a certain result. I feel frightened now.
And another nice resource: Math 216 (Foundations Of Algebraic Geometry) Notes.