This article is a great place to start for those wanting a deeper understanding of how the various browsers render XHTML lists by default (hint: IE is the odd man out), and how to negate those differences with CSS to create a consistent cross-browser appearance. Kaspars walks us through the default rendering (with beautifully rendered examples!) and the CSS needed to counter them. He also gives a few practical examples on how to style your lists for greater visual appeal.
CSS-Tricks has started releasing semi-regular video screencasts (think: video, but of a computer screen) covering topics rather useful to the beginning-to-intermediate CSS designer, such as how to move from a Photoshop mockup to a CSS-based website. I’ve only watched the first two so far, but if they’re any indication of the overall quality, this is definitely a page to bookmark.