Some sites are collections of other useful material.  Scoop.it! is a great (free) tool to do this yourself.  It's a nice way to share what you have found with others.Here are some that I've put together:
 
elt-training - a collection of sites for CPD
Lesson ideas on the web.
Grammar sites.
'Flipping the classroom' - useful sites for trainees

This site, 'English Teacher Websites' also has links to all sorts of useful stuff - resources, blogs, jobs etc...

Blogs are a great way of getting practical information such as ideas for lesson plans, but they are also particularly good at keeping you thinking, reflecting on your practice and motivating you, making you feel that you are part of something much bigger than your four classroom walls. Here are links to some of my favourites (including my own!).
ICT in ELT Jo Gakonga
A Muse Amuses
An A-Z of ELT
Marisa  Constantinides - TEFL Matters
Nik's Learning  Technology Blog     Sean Banville's Blog    TEFLtastic with Alex  Case  ELT Resourceful

ELTchat is a brilliant way to use Twitter to connect with other elt professionals around the world.  Every Wednesday at 12pm and 9pm GMT elt types of all sorts gather and tweet for an hour on a subject that is suggested and voted for during the week on www.eltchat.org

After each 'chat' a summary is produced and these provide a great archive of thoughts and useful links on a wide range of subjects - you can find these on the website. It's very friendly - all you need to do is search for #eltchat on Twitter and remember to include the hashtag when you send your tweets!