The Internet Public Library is a public service organization and a learning/teaching environment founded at the University of Michigan School of Information and hosted by Drexel University's College of Information Science & Technology.
The IPL offers to answer reference questions online (unlike the AADL), with a listed 3-day turnaround time. Like the AADL, they don't like answering homework questions.
Home page: http://www.ipl.org
In 2010, the Internet Public Library (IPL) merged with the Librarians' Internet Index (LII) to create ipl2: Information You Can Trust.