Typetester is a wonderful little online tool that lets you quickly compare just about every aspect of type that can be altered using CSS.
The tool lets you compare font, leading, size, word spacing, weight, text decoration and much more.
Also, it’s a great refresher for CSS text attributes, and Typetester conveniently highlights the fonts which are considered Web browser safe. Silly me had forgotten all about little ol’ Trebuchet MS (though feel free to forget about Comic Sans any time).
Also, check out the tutorials category for more tools useful for online journalism types.