The Dashboard feature is pretty cool.
It uses little "widgets" to display info on your desktop. Stuff like weather/stock quotes/phonebooks.
I am excited for Automator.
I do a lot of repetitive things when I am designing and it sounds like Automator will be able to help me out with that.
Safari has a cool new RSS feed to keep you up to date on all the news and different sites you monitor.
It seems like a lot of little features that might add up to be worth spending the dough on... but I usually wait to test drive before I buy.
Here is a link to Tigers page:
http://www.apple.com/macosx/
It's $129 for a single user but if you know anybody who teaches or is in school they can get it for $69.