Andrew Zack is the president and founder of The Zack Company, Inc. Zack has been a literary agent since 1993, and has an extensive background in publishing and bookstore management. He is primarily looking for non-fiction (see his extensive list of topics), but also takes fiction.
Zack has been blogging for several years at All Thats New(s) From A to Z. He is definitely interested in author rights, and is a former chairperson of the Association of Author Representatives Royalty Committee, working to keep things fair for authors.
Here's a sampling of his posts:
On queries: Zack provides links to several excellent articles on effective query letters.
On ebooks: Zack's Huffington Post article discusses the 'beginning of the end' of traditional books.
On formatting: How to format your electronic submission so agents and editors can read it easily on their ereaders.
On requests: Believe it or not, some authors who have gotten requests from agents don't actually send the chapters. Zack talks about why this happens.
On self-publishing: An interesting analysis of the quality of indie books. See if you agree with Zack.
On royalties: Zack details ebook royalty rates, and what you need to know.
If you queried an agent and he requested chapters, would you be prepared to hit 'send' right away? Why or why not?