Agent Research and Evaluation  
   Provides complete information on literary agents and their track record of sales for authors, often including dollar figures in the US, Canada and the UK.
   http://www.agentresearch.com/

Writers Net  
   Not agents themselves but "a matchmaking resource for writers, editors, publishers, and literary agents on the Internet". Free service run by the husband of a writer.
   http://www.writers.net/agents.html

Everyone Who's Anyone in Adult Trade Publishing  
   A free online directory of almost 2,000 of the top literary agents, editors and publishers of adult trade books in the US, UK and Canada, including e-mail addresses and websites.
   http://everyonewhosanyone.com

Vetted, Non-Fee-Charging Agents  
   A list of vetted agents from author Natalie R. Collins who also wrote Buy This Book and I'll Wash Your Car: How to—and not to—Get a Literary Agent. Ebook for sale on site.
   http://www.nataliercollins.com/agent-information/agent-listing.php

Writer's Market  
   A fee-based service which offers significant amounts of information on hundreds of literary agents in all genres. Also has market listing for magazines and publishers. The grandaddy of agent resources.
   http://www.writersmarket.com

Preditor and Editors  
   A huge listing of agents and scuttlebutt on the black hats. If an agent has a bad reputation, you'll probably find the dirt here.
   http://www.anotherealm.com/prededitors/pubagent.htm

Publishers Marketplace  
   Provides membership information for publishing professionals and provides web pages for writers and agents to promote themselves.
   http://www.publishersmarketplace.com/

Agents' E-mail Addresses  
   This is a list of literary agents' e-mail address and also agency websites if they have one. (ed: LONG list)
   http://www.writers-free-reference.com/agents/index.html