a4esl.org

A great site that has lots of quizzes, grammar tests, crossword puzzles, etc, to help you practice English.  There is also a bilingual page that lets you use your first language and English.

http://world-english.org/

You can do a variety of English exercises and tests on this page.  Some of the tests give you feedback about your score.

http://blog.shankarganesh.com/2007/12/21/how-to-improve-your-english-online/

This is a fantastic page full of lots of advice on different ways to practice your English online.  Many links to interesting websites are included - be sure to have a look!

http://www.gettingdownunder.com/2008/04/20/ielts-preparation-video-useful-stuff/

This is a video which explains the IELTS test in detail and offers suggestions and study tips.

http://www.esl-lab.com

This is a huge site with over 175 listening activities.  Choose the best level for you, and practice listening, answering multiple-choice questions, etc.

http://www.ezslang.com

Free activities to help you learn natural conversation and understand the slang that native speakers use.

www.oup.com/elt/openforum

This website is produced by Oxford as an addition to the textbook series: "Open Forum".  These free audio downloads provide excellent listening practice.  Very useful for the IELTS test!

http://www.common-mistakes.net/

Spelling is very important in the IELTS test (Writing & Listening).  This site has a lot of activities to practice frequently misspelled words, misused words, and commonly confused words.  Choose from beginner, intermediate or advanced level.