Although I haven’t even tackled the big new things in Tiger (smart folders, automator etc.) I keep making happy accidental new discoveries. Like this beautiful screensaver, which renders a three dimensional visualisation of any RSS feed in your Safari bookmarks. Choose an RSS feed (such as the one for this site, or as I do, the feed for Guardian Unlimited), make sure you’ve bookmarked it, and then select this feed under the options for the RSS visualiser screensaver in System Preferences.
Of course being an Apple screensaver, it’s in the detail that it shines: when the screensaver’s up, if a story catches your eye you just hit a number key to read the full article.