For those of you who do not know, "scholia" (singluar scholium) are the marginal commentary notes on classical texts (and possibly stretched to include some of the ancient scholars works in their own right). Until last weekend, I knew next to nothing about ancient scholarship. Now I know a little bit. Last Saturday, while proctoring an exam, I read the kindle free sample of Eleanor Dickey's Ancient Greek Scholarship: A Guide to Finding, Reading, and Understanding Scholia, Commentaries, Lexica, and Grammatical Treatises: From Their Beginnings to the Byzantine Period, which first discusses the scope and format of ancient scholarship in general, and then about the bodies of scholia on texts (such as scholia on the Iliad or Euripides' works). The second half of the book is essentially a textbook on how to read ancient scholarship. It sounds great, but I have so many other things to read that I have not bought the full version yet.
Homer Multitext ran a post about a particular book with scholia on the Iliad. The post discussed an individual text of the Iliad (and a specific folio within that text) and the unique summery in the scholia of the particular manuscript. It then compared this text with other texts of various time periods. The article was very interesting and I recommend it.