I'm so glad I subscribe to Chuck Sambuchino's Guide to Literary Agents blog. Apart from information on established agents it provides lots more. It introduces new agents, notifies of agency closures, interviews writers at all stages of their careers and has articles on how to hone the dreaded pitch, cover letters and so much more, often reminding me about something I've forgotten as well as great new information. There are giveaways too.
This link came into my Inbox yesterday. Among the blogs are some I already follow - Rachel Gardner's Rants and Ramblings On Life As a Literary Agent and Kristen Nelson's Pub Rants - but others were new to me. They are all now on my list of blogs to follow on a regular basis.