AJATT is a crazy site, with really long and funny posts about learning Japanese. The advice on the site is useful for learning any language, though. The author has great advice on staying motivated for language learning.
Antimoon is a blog that suggests a certain method for learning English, which involves lots of input. Ask Antimoon is a site where you can get expert answers on questions about pronunciation, grammar, or other language issues.
English Harmony is a blog about how to gain fluency in English. It has good advice on ways to practice English and how to motivate yourself.
Anki is an SRS tool that allows you to create flash cards and review them at just the right time, before you forget. It's very flexible and can be used to study any kind of material.
Brainscape is a tool for studying flashcards on the Internet or on a mobile phone. They have some English vocabulary sets that you can study. Those are OK, but the real value is that you can create and study your own flashcard sets.
Lang-8 is a site where you can write a journal entry in English and have it corrected by other English-speaking users. It can be difficult to find people to correct your writing at first, but once you ask a few people to add you as a friend it gets a lot easier.
Lingq is a language learning site that provides a variety of tools, including podcasts, live chat, and a tool that keeps track of vocabulary that you're learning. There's a free version and paid services.
Netspeak is a kind of phrase search engine. You can find out what words are most commonly used together by doing a search. (For example, type in "most commonly ?" to see how popular "most commonly used" is as a phrase.)
Phrases.net is a big dictionary of English phrases. There are tons of phrases on the site. Unfortunately, the definitions are written in a technical style that can be hard to understand.
RhinoSpike is a site where you can upload an English text and an English-speaking user will upload a recording of themselves reading it out loud. It's a good tool for practicing listening and reading together at the same time.
PhraseMix has used RhinoSpike to record some of the Language Terms explanations on this site.
VocabSushi teaches English vocabulary words. It has example sentences for each word that are taken from online news articles. The words are difficult, but good for advanced English learners.
Wordnik is like a dictionary, but it includes extra information that dictionaries don't, like example sentences, phrases that the word is a part of, Twitter results for each word, and statistics on the word's popularity.
dotSUB is a site with lots of subtitled videos. The videos are on a variety of topics, but they're also in a variety of languages, so you'll have to search through them to find the ones that are in English.
engVid is a site with hundreds of free video lessons. Lessons are taught by native English-speaking teachers who stand in front of a whiteboard and write out notes while they teach.
TED is a series of conferences where experts share "big" ideas on a variety of topics. There are videos of each talk on this site with subtitles available under the video.
You've certainly heard of YouTube before, but did you know that there are a lot of YouTube videos with English captions? There's a PhraseMix post on how to search for YouTube videos with captions.
