Niddah:

1. Niddah: R. Mordechai Willig's shiurim (Hebrew PDF, Eitan Mayer)
   
2. Review of the above (Hebrew PDF, Eitan Mayer)
   
3. Exercise to review the above (Hebrew PDF, Eitan Mayer)
   
4. List of Mekorot for R. Willig's shiurim (Hebrew, PDF)
   
5. Brief summary of Shulchan Arukh with Shakh (English, MS Word) 
   
6. Brief summary of Shulchan Arukh with Shakh and Taz (English)
   
7. Notes on Yeshivat Har Etzion Niddah mekorot sheets (English, MS Word)

8. R. Dovid Miller's shiurim (English, Aton Holzer)