Here you find some useful links to improve your English skills and for extra English practice.
Suggestions are more than welcome!
Dictionaries:
Free dictionary www.thefreedictionary.com
Photo dictionary http://www.eflnet.com/vocab/index.php
Picture dictionary http://www.pdictionary.com
Dictionary port-ing http://www.m-w.com
Dictionary babylon http://www1.uol.com.br/babylon
Urban dictionary http://www.urbandictionary.com
Dicionário Michaelis http://michaelis.uol.com.br/moderno/ingles/index.php
Cambridge dictionary http://dictionary.cambridge.org
Glossary http://www.harcourtschool.com/glossary/esl
Infovisual http://www.infovisual.info/volume_en.html
Picture dictionary http://www.esclub.gr/PictureDictionary
One look http://www.onelook.com
World atlas http://www.worldatlas.com/aatlas/world.htm
Just the word http://193.133.140.102/JustTheWord
Visual Merriam Webster http://visual.merriam-webster.com
Cool links: 
Ibeu www.ibeu.org.br
Languge guide http://languageguide.org
Fun facts http://funshun.com/funfacts
Tune into English http://www.tuneintoenglish.com
Funny jokes and pictures http://www.toofunnyjokes.com
ESL Flaschcards http://www.eslflashcards.com
Touchstone http://www.cambridge.org/us/esl/touchstone/student/index.html
British Council http://www.britishcouncil.org
The New York Times http://www.nytimes.com
Rio Daily News in English http://www.topix.com/br/rio-de-janeiro
Phonology http://www.uiowa.edu/~acadtech/phonetics/english/frameset.html
Letras de musica http://www.letrasdemusica.com.br
Vagalume http://www.vagalume.com.br 
Slang http://www.manythings.org/c/r.cgi/slang
Daily cartoon http://www.glasbergen.com
Idioms http://www.goenglish.com/Idioms.asp
Sozo exchange http://www.sozoexchange.com
Interchange http://www2.cambridge.org/interchangearcade/main.do
Zap English http://www.zapenglish.com/pt/vocabulario-comidafrutas.htm
ESL Gold http://www.eslgold.com
Minimal pairs http://www.manythings.org
Site for Kids http://www.uptoten.com
Amazing quizzes http://www.funtrivia.com/quizzes/index.cfm
BBC http://www.bbc.co.uk/worldservice/learningenglish
For Better Life http://www.forbetterlife.org
CNN – Student News http://www.cnn.com/studentnews
Discussion Topicshttp://www.btinternet.com/~ted.power/discuss.html
Film Wise http://www.filmwise.com/main/index.shtml
Go 4 English http://www.go4english.com/index.php
Grammar
Grammar Ideas http://edition.tefl.net/category/ideas/grammar
My English grammar.com http://www.myenglishgrammar.com
Isabel Perez http://www.isabelperez.com
Grammar quiz http://www.saywhatesl.com/quizes
Grammar net http://www.grammarnet.com
English hilfen http://www.english-hilfen.com
Grammar and vocabulary http://www.grammar.cl
Learn English http://www.learnenglish.org.uk
Grammar exercises http://elt-marketing.oup.com
Grammar http://owl.english.purdue.edu/handouts/print/grammar/index.html
Grammar quizzes http://www.usingenglish.com/quizzes
Grammar 200 http://web2.uvcs.uvic.ca/elc/studyzone/200/grammar/index.htm
Grammar girl http://grammar.quickanddirtytips.com/default.aspx
Grammar http://elt-marketing.oup.com/q/1d81SEAY95rw/wv
Purdue.edu http://owl.english.purdue.edu
Grammar handouts http://owl.english.purdue.edu/handouts/print/grammar/index.html
English tenses with cartoons http://www.englishtenseswithcartoons.com
Listening
Podcasting in education
http://www.apple.com/education/digitalauthoring/podcasting.html
Diglyrics – lyrics + youtube videos http://www.diglyrics.com/en
Elllo – Online Listening Activities http://www.elllo.org/english/home.html
Repeat after us http://repeatafterus.com
Voa news http://voanews.com
