I have added a Readers page that can be accessed through the Learn Greek page at either Greek-Language.com or GreekLinguistics.com. The new page provides downloadable copies of a number of readers designed to supplement ones study of Ancient Greek.
I have found far more of these for Classical Greek than Hellenistic Greek. If you are aware of any good Hellenistic (Koine) readers that are available for download, please let me know and I will add them. You can contact me through the Contact page.