Pull-Ups
I was going to write something about pull-ups, but there's so much good information out there I'll just link you up:
If you can't do any pull-ups, or if you struggle just to do one (that's where I started out at the beginning of this year) give Pullup Training for Women and/or The Road to Your First Pull-Up a good read. The former article talks about using Jump-Stretch bands to assist, which seems like a much more economical solution than the Active Cords I used (I swear they were cheaper way back when I bought them).
Regardless of how many pull-ups you can do to start, you should definitely read The Application and Creation of Pullup Power first for invaluable advice about engaging the big muscles of the upper back rather than just pulling with your arms.
That's really all you need to know to get on the road to respectable pullup power. Beyond that, there's The MonkeyMaker, and a great discussion on Crossfit concerning how high to pull yourself (click the "Archive through..." link at the top of the page to get back to the beginning of the discussion). From that discussion, take special note of this post by Greg Everett and watch the "Big Fat Pullups" video he links to. The guy just flys over the bar.