Literary Agent Jessica Faust has a great blog on her agency's site, Bookends. For anyone looking to get an agent, this is a blog you should absolutely be reading often. She has great information and it is a chance to find out what goes on in an agent's head.
A recent post that caught my eye was one on writing a good nonfiction book query. It was informative, but it also showed that agents aren't seeking perfection, they are seeking good projects or stories.
Read her blog post here.