I've been reading some of Noah Lukeman's books. He is a literary agent and gives lots of advice to wannabe writers about how to edit, how to write query letters, and how to actually make contact with agents. He notes that some writers give up too soon, since they only approach maybe 3-4 agents, and those agents may or may not be appropriate for the work. Lukeman recommends approaching a minimum of 50 agents, more if you feel ambitious.
From his e-book, How to Land (and Keep) a Literary Agent, he recommends some free resources to find agent names. They include:
www.publisherslunch.com -- a (free) daily newsletter that gives publishing news and publishing deals. Agent names with the works sold are reported here. There is also a paid version for this newsletter.
www.publishermarketplace.com -- a website that includes a search members link to find accurate contact information, links to the "Top 10" most visited agents, and general news etc. about publishing. Again, there is also a paid access area, but what's described here is free.
www.publishersweekly.com -- contains a "deals" link, although the agents reported here will tend to be established and therefore less anxious for new clients, free articles and information, and a free weekly newsletter.
You can also do Google searches and Google Blog Searches to find listings for specific agents and editors. The blog search might be useful even for general terms such as "literary agent" or "literary agency."
Twitter: there are agents and agencies on Twitter. You can search for these using http://twitter.com/agentquery
You also can look through the acknowledgements pages of similar books. You can find more books that mention a particular agent by going to www.books.google.com, then in the Search box type the agents name in quotes, and then the word "Acknowledgements."
www.writersmarket.com -- offers a free newsletter.
www.writersdigest.com -- has free articles and a free newsletter. They also do an annual list of 101 best websites for writers.
www.guidetoliteraryagents.com/blog -- companion blog to WD Guide to Literary Agents.
www.agentquery.com -- has a free searchable database of agent and agency information.
www.absolutewrite.com -- some resources
NOTE: This list was compiled from Noah Lukeman's e-book, How to Land (and Keep) a Literary Agent.
5 hours ago