Amy Hoy has written a great tutorial running through the Rails console that's suitable for both complete novices and experts (there are a couple of tricks she mentions that I didn't know at least!). Amy appears to have taken up Slash7 with a new zeal lately, so let's hope we'll see more great content like this on her blog through 2007!

"How To Think Like A Computer Scientist" is a range of online books (distributed under the GNU Free Documentation License) developed by various authors each focusing on a different programming language and explaining computer science concepts with it. Elizabeth Wiethoff has now started the Ruby edition and has made her work so far available online.