The web is a wonderful place to explore ESL and learn English.  Here are a few sites.

Other Pronunciation Sites

Confident Voice:  This webiste offers courses and programs, but also some free resources, including a 4-week eCourse.
Sunburst Media:  an excellent and well-categorized link list dedicated to pronunciation.

Online ESL Communities

These communities can be a good way to meet other people who want to practice their English, and to post questions to forums.  Many of them have additional resources, like tests, vocab building matierials, etc. 
EFL Classroom 2.0
EnglishBaby
English-test.net
UsingEnglish.com
EnglishForums.com

General ESL Links

Tower of English:  This site is a collection good and well-organized collection of links, but takes things a step futher by having a "Your Turn" tip for each link that helps you get even more out of your learning experience.

John's ESL Community is the only website dedicated to the ESL/EFL community that offers
free class websites for teachers. The site also offers free downloadable lessons , worksheets and activity generators for teachers. For students, there are hundreds of on-line activities designed to help them improve their English, including games, quizzes and on-line tutorials.

ESLgold.com provides all kinds of free materials for teaching and learning English.  Resources are organized by skill and level for quick and easy access.

Karin's ESL Party Land has a section for students with interactive quizzes, as well as resources for teachers of ESL.