There are many web sites containing useful worksheets, lesson plans and games for learning and teaching English.
http://www.oxfordlearnersdictionaries.com/ Gives pronunciation with voice recording, a clear explanation and sample sentences. I suggest my students bookmark this web site on their phones and use it to look up new words.
Speaking and Conversations
http://www.esldiscussions.com/ – Great topics for discussions. Questions for pair work in Word and PDF format.
http://iteslj.org/questions/ – Conversation Questions on many topics
http://www.englishgrammar.org/ – Grammar lessons with an emphasis on writing
Worksheets and other resources
http://busyteacher.org/ Thousands of free printable worksheets.
http://www.teach-this.com/ contains hundreds of professional ESL and EFL teaching resources to help you teach all the core skills associated with language learning: speaking, listening, reading, writing, vocabulary and grammar as well as specialized categories such as Business English. Need to pay for a subscription to access all content.
http://www.breakingnewsenglish.com/ – Current affairs stories with lesson materials.
http://www.englishpage.com/ Free online English lessons & ESL and EFL resources
http://autoenglish.org/ Many great resources including worksheets.
https://en.islcollective.com/ – many printable worksheets.
http://www.onestopenglish.com/ – 30 day trial available otherwise a subscription is required.
http://www.5minuteenglish.com/ – useful resources.
http://www.eslflow.com/ – a very busy website with many resources.
http://usingenglish.com/ A large collection of tools and resources for students, teachers, learners and academics, covering the full spectrum of ESL, EFL, ESOL, and EAP subject areas.
http://www.esl-lab.com/ – Listening lab.
http://www.bbc.co.uk/skillswise/english BBC Skillswise English
http://www.bbc.co.uk/learningenglish/ Learning English.
Puzzlemaker – http://www.discoveryeducation.com/free-puzzlemaker
Links to more sites
This article on ELT Experiences has links to more sites.