Reasons for Learning Esperanto - An interesting compilation of arguments over the merits and limitations of Esperanto, by Ken Caviness. - http://personal.southern.edu/~caviness//Eo_unue/Eo_unue.html
A Key to Esperanto - Concise, accessible overview of Esperanto grammar. - http://www.esperanto-chicago.org/key.htm
Esperanto FAQ - Oftaj demandoj Part 2/2. - http://www.faqs.org/faqs/esperanto/faq/part2/
Brief Note on Esperanto - A more academically flavored FAQ written by David Jordan, Professor of Anthropology at UC San Diego. - http://weber.ucsd.edu/~dkjordan/es/esperant.html
Esperanto Studies and Interlinguistics - An index page for scholarly work on Esperanto and constructed languages. - http://www.esperantic.org/ced/studies.htm
David Poulson's Esperanto Column - An ongoing series of short articles on many aspects of Esperanto, begun in June 1998. - http://www.suite101.com/articles.cfm/esperanto
Esperanto - An Overview - Another FAQ written by Don Harlow. - http://www.webcom.com/~donh/efaq.html