What are your top supplement books for learning Korean?
I currently use https://www.goodreads.com/book/show/5507477-basic-korean
I love Integrated Korean, the books and workbooks. I also have The Sounds of Korean by Mihoo Choo and William O’Grady.
Also, the website How to Study Korean is a great resource.
For study inspiration, I love reading the blog Hangukdrama - she’s moved on to studying Japanese now (I think - it’s been a while since I visited) but has gained enough fluency in Korean to be paid to translate articles. She kept a detailed blog on her study techniques, and she now reviews Korean textbooks and details her experience with TOPIK. Super inspiring.
I use Korean Made Simple by Billy Go. There's three books in the series and I'm only on the first one but I really like it so far :)
As others have said Talk to me in Korean (TTMIK) is awesome. They have all of it as PDF files on the website for free or you can watch their videos or listen to their podcasts. They also sell books that are more in detail then the PDF files. I also an using "Korean Stories For Language Learners: Traditional Folktales in Korean and English" It gives vocab for each story, cultural notes, comprehension questions, and writing exercises for each story. In the begging the stories are a few lines then gradually increase to about 4 pages. It also comes with a cd of a native speaker reading the stories as well. so far the stories are pretty funny and I am learning some interesting vocabulary.
Book wise I am using the ewha university book series, and I have Korean grammar for speaking ( http://www.koreanfashionista.com/korean-books/korean-grammar-speaking.html )
Talk to me in Korean though is a really great resource, I also sometimes look at Korean from zero. I also just randomly browse Korean sites, you can run across some really great resources on the kid sites sometimes lol. http://jr.naver.com/ http://www.kebikids.com/
http://tadaktadak.co.kr/taja/jari.html?type=0 <-- This site here has also helped a bit with my typing
Also a good little gem I found is a Korean bookstore that does have an american site where they seem to ship from america. Only down side is if you can't navigate a site in Korean maybe tricky since it is in Korean (and making an account is in Korean) But I have ordered Korean books from them no problem in the past and shipping was free over $50 ( http://us.aladin.co.kr )
I sorta just went on a sleepy resource dump lol.