Even though you already mentioned it, endic.naver.com is the best resource. However, I've discovered that most of my students use it solely to look up a word meaning.
They have no idea how useful that site is. For example a student can type in "성격" and the first thing that shows up is the definition "personality." But if they click on "personality" they can get derivatives of the word, synonyms/antonyms, useful example sentences, the English definition of the word, idioms, a list of verbs that are frequently used with the word, explanations on how to use the word and in what situations using the word is or is not appropriate, and links to Korean websites with more information about the word.
If a student reads an example sentence and comes across an unknown word, they can hover over that word (older versions have to click on it) and the definition will appear.
Students can also save words and create their own mini dictionaries. They can make folders to divide different topics. You can have the students look up words like "boil" and "spatula" and then save them to a Cooking folder. The students can then print the list for study or there is even a quiz tool that the students can use on the site.
Off-topic to this post, but hopefully still useful:
I highly recommend this site when introducing new vocabulary or grammar structures. The example sentences usually come from real-life sources such as interviews, news reports, movie quotes, etc. and are faaaaaaar better than the example sentences found in my textbook.
You can also type in a full sentence and the site will bring up similar sentences that have already been translated into Korean.
Try typing in 행복속담 or 행복명언 in the search. 행복 means happiness and 속담/명언 are idioms or sayings. A whole list of popular/wise quotes on happiness will appear. Replace this with 인생 (life) 희망 (hope) 믿음 (trust/faith) and you can introduce inspirational sayings to your class complete with Korean explanations.
And lastly, if you are learning Korean and you consider yourself to be at the intermediate level, this is the best resource for continuing your Korean learning. You can directly search for grammar structures and get access to their meanings, appropriate usage and dozens of example sentences. For beginners, definitely stick to books until you get the basics down. But for higher level learners who are looking for ways to expand their speaking abilities, this is the way to go!
Anyways, I think I will repost this all on a new thread... but I hope the top part is at least useful for you zanmwebb. I think you could easily spend a class period showing the students how to fully utilize the website. :)
