Superior links here.
You can find all the translations for the Code Geass drama CDs + their respective MP3s,Sayoko diary entries,Ashford Novels + the pages, and the History Lessons here.
Except for -
Sayoko's Diary Entry #8 - The Maid Sees All!
Stage 5.831- Orange Peel
Stage 0.916 - Black King
Stage 21.534 -The Final Invitation
History Lesson 2,4 ,6,7,8 and 9 are just summaries we still need the actual transcripts for them.
Here you can find all of the subbed Picture Book Dramas.