Gabriel Wyner is a self-taught polyglot who, besides English, speaks four other languages (German, French, Russian, Italian) and is perfecting Hungarian. On his blog towerofbabelfish.com he writes: "I studied a language in high school, and left high school, like most people, without much of an idea what I spent all those years studying. I was left with a disturbing question: I worked hard and I had good teachers; what went wrong, and what could I do better?"
He provides a lot of suggestions on his blog on what others in his situation can do to learn a second (third or fourth) language. He is big on flashcards, particularly Anki. He also shares tips on memorization techniques.
Benny "the Irish Polyglot" Lewis speaks nine other languages (Irish, French, Italian, Esperanto, Spanish, German, Dutch, Portugeuse and Mandarin - plus American Sign Language). Benny calls himself a language hacker who can help others learn another language using his unique methods.
He sells a package of tips and techniques from his website speakfromday1.com that promotes speaking over studying. He also writes a blog fluentin3months.com that chronicles his language-learning adventures around the world.