This is a nice site with some good information on Polyamory written with an easy to read style.
Polyamory? by Franklin Veaux
Franklin tackles some of the common questions about Polyamory, misconceptions, issues, and even provides some advice.
Though not perfect, most of the information if very good and I highly recommend checking it out. Good site for poly-curious as well as experienced poly's.
The title for this post is an active link to Franklin's site. Click and enjoy!