I'm using and enjoying this book http://www.amazon.com/Elementary-Korean-Second-Ross-Ph-D/dp/080483976X/ref=sr_1_1?s=books&ie=UTF8&qid=1283026813&sr=1-1 Suitably thorough and aimed at adults. For a non-free online source I'm a big fan of Koreanclass101.com. They do seasons (beginners season 1, 2, 3 etc, intermediate seasos, podcasts) which if you follow chronologically gives you a a lot of great grammar points. This is delivered via one pdf and one audio file per lesson. The pdf has a transcription of the dialogue plus details on that lesson's grammar point. The dialogue is great because it's colloquial, everyday Korean, and not slow, classroom Korean (or slow Rosetta Stone audio). You can try it out for free for one week to see if it's interesting.