If you've heard about Ruby but you don't want to go to the bother of installing it just to find out you don't like it, then you can use this interactive tutorial from one of the strangest cats (in a good way) I've seen pimping any programming langauge, Why the Lucky Stiff.
It just runs in your browser (though there are reports that it doesn't work in Opera), patiently waiting for input to send to what's probably something akin to irb. With the magic of XMLHttpRequest and the moo.fx effect lib that _why was pushing a few weeks ago, you can run through a few tutorials on how ruby works. It's quite a lovely experience.
A friend of mine who's a security researcher has been trying to break it for the past half hour, unsuccessfully.