The PimpNotes Grids
That should me very helpful for the step 1 preparation.
PimpNotes.org is an open-source notes project for medical students and doctors in training. The site hosts free notes, guides, books, or any other materials created by and for medical students and residents.
It currently hosts a complete systems-based pathology charts (“the grids”) and pathophysiology flash cards (in progress). an open-source guide to usmle step 1 is forthcoming–created and maintained by those who are closest to the material–the students themselves.
You can also find the link in the Download page of usmlemd.
I don’t have time to go trough all the information, but you guys can give a feedback about the grids.