If you're totally new to the world of accordions, Accordion 101 explains the basic types of accordion and gives some of the history behind them.
Hans Palm's Accordion Page. This is one of my favorite accordion sites out there (even if it's only "out there" via wayback machine now.) Useful info, interesting information, and a page of accordion jokes!
Accordion Revival. Everything I know about the guts of accordions and how to take care of them is stuff I've read from this incredibly detailed, expert site. This guy knows what he's talking about.
And of course, if you're looking for some beginner accordion music books, look at the bottom of the main accordion page.
