James Edward Gray's series on higher-order Ruby -- based on the fantastic Mark-Jason Dominus book Higher-Order Perl -- was one of the most useful and interesting resources on the Web for me when I was learning Ruby. He wrote the Ruby Quiz anthology for the Pragmatic Programmers, and his book on TextMate's going to be released next week.
I highly recommend it. Although I've used TextMate before, I've never bothered to really learn it -- it was too easy to depend on my vi skills. As amazed as I am to say this, after going through this book to grep out the essentials, I could actually see myself abandoning vi forever. Don't quote me on that -- old habits die hard. But I could see it. The software's utterly kick ass, and I have to give this book a lot of credit for making it really easy to get to the juicy stuff very quickly.