You can find a large number of practice tests/actual tests, useful IELTS lessons, tips, books, on the following web sites:http://www.ielts.org
The official IELTS website - it also contains a test centre locator function, which can find your nearest test centre. http://www.britishcouncil.org
The British organisation that runs IELTS. http://www.cambridgeesol.org
One of three organisations that run IELTS. http://www.idp.com
The Australian organisation that runs IELTS. http://publishing.cambridge.org/ge/elt/exams/ielts
Cambridge University Press IELTS books are available on this website. You can buy books as well. http://www.aapress.com.au
A renowned website selling many IELTS books. http://www.ielts-exam.net
A lot of sample questions and answers can be found on this web site. http://www.ieltscuecard.com
A websites that offers a great resource on IELTS Cue card and a large number of questions which can help you to practise. http://www.engvid.com/english-exams/ielts
A rich collection of IELTS videos that would definitely help enhance someone's English skill as well as IELTS skill.
ielts-simon.com / www.dcielts.com Both sites are really great resources for IELTS preparation
www.ieltsbuddy.com IELTS Buddy is a great site which focuses on important areas such as vocabulary and grammar which are ignored by students most of the time.
www.ieltsliz.com A lot of useful tips are given covering all aspects of IELTS.