Here are some of the URLs I find interesting:
http://www.teclasap.com.br/ - Here you can find information about authors like Michael Jacobs, Jack Scholes and Ulisses Wehby de Carvalho. You can also subscribe to a free newsletter that includes enlightening explanation on common errors; hard-to-find words, expressions and slang, etc.
http://www.englishpage.com/ - This site offers free online English lessons and ESL/EFL resources. Very useful for teachers and students.
http://dictionary.cambridge.org/ - Dictionaries online offered by Cambridge University Press. The categories include: Advanced Learner’s Dictionary; American English; Idioms; Phrasal Verbs; French / English and Spanish / English.
http://www.lingual.net/main.php - A movie site for English Language learners. You can't miss it!
http://www.teachit.co.uk/ - According to its developers, Teachit.com specializes in English, Drama and Media Studies, and they offer over 5,000 pages of classroom materials, schemes of work, lesson plans and teaching tools created by working teachers and constantly growing.
http://www.churchillhouse.com/english/downloads.html - A page from which you can download free English language software (CALL) or access ready-to-use classroom materials for English language classrooms.
http://www.webenglishteacher.com/ - In Carla Beard’s words, “At Web English Teacher educators can take advantage of online technology to share ideas and to benefit from the work of others. Beginning teachers can find guidance; experienced teachers can find inspiration. Think of it as the faculty library and faculty workroom on a global scale. Because the most important part of teaching isn't the technology.”
http://hjem.get2net.dk/niels_quist - Links and resources on English teaching; shareware programs for download that may be of interest for learning / teaching English as a second language; a list of links to shareware download sites, and hints on how to search for and find other shareware programs on the Internet. Also, a list of common and special search engines, an explanation of different types of what is called "search engines" in an everyday language, hints on searching more effectively, and links to further reading about the topic.
http://www.english1.org.uk/ - This site has been set up to be a forum for teachers of English to gather and to publish, in these pages, the ideas and resources they would like to share with other visitors.
http://www.english-to-go.com/ - “English-To-Go® teaching resources are used by thousands of teachers around the world. A subscription will allow you to use the resources as often as you like.” You can choose from hundreds of lessons from their searchable library. “You can save hours of preparation time and empower your students to think independently and form opinions. Resources are updated regularly. English-To-Go teaching resources are current, topical and international. They include Instant Lessons, Instant Workbook, Anna Grammar, Weekly Warmers and Max Vocab.”
http://www.ldoceonline.com/ - Here you will find a free online version of the CD-ROM of the Longman Dictionary of Contemporary English. A must for English learners, as well as for teachers.
http://www.eslcafe.com/ - Dave’s ESL Café is, in the author’s words, “the Internet’s meeting place for ESL/EFL teachers and students from around the world.”
http://www.englishclub.com/ - This is a comprehensive portal that caters for teachers and students. You can’t miss it.
http://englishonline.sites.uol.com.br/ - Here Paulo Hardt helps students and teachers of ESL/EFL find thousands of links with activities, grammar explanation, and many other resources to improve their English.
http://www.wsu.edu/~brians/errors - Here you'll find innumerable words and expressions that are commonly used in a wrong way. The author explains how they should be used. A very useful site.
http://a4esl.org/q/f/ - On this site there are activities to help students with English as a Second Language. This project of The Internet TESL Journal has contributions by many teachers.
http://www.peevish.co.uk/slang/links.htm - Online slang dictionaries and language links: British slang and language related sites; general English slang and comparative English-American language dictionaries; US slang and language related sites; Australian slang; New Zealand sites; South African sites; foreign language sites; drug related slang; 'black' slang and rap; gay/lesbian slang sites; crime and prison slang; other specialist slang sites; miscellaneous dictionaries and other language related resources. This site is a must! Don't miss it!
http://www.usingenglish.com/ - According to the owners of this site, usingenglish.com provides a large collection of ESL tools and resources for students, teachers, learners and academics. There are teacher handouts and printables that cover a wide variety of subjects. Cool!
http://www.focusenglish.com/ - A site dedicated to helping ESL/EFL learners develop conversational English skills. At FocusEnglish.com, you can: listen to native speakers talk about various topics; learn useful idioms; learn common words and phrases; test your vocabulary skills in everyday English; practice responding, in English, to real-life conversations; listen to native speakers give sample responses. Check it out as soon as possible.
http://www.newseum.org/todaysfrontpages/flash - A site where you can read the front pages from well-known newspapers in the world. Nothing could be more practical for curious readers!
http://www.manythings.org/c/r.cgi/slang - Here you will find a lot of American slang in sentences that can be heard in everyday conversation. Check out their main page as well: http://www.manythings.org/ has a lot of useful information for everybody.
http://www.thebeatles.com/ - Here you'll see photos and listen to parts of interviews featuring The Fab Four from Liverpool. Teachers who make students practice listening in the classroom will certainly find this a useful tool.