It would be easy to go on and on about great software--some well-known, some fairly obscure but to those in their respective niches--but suffice to say that a good argument can be made to keep Mac OS 9 functionality around, at least for awhile longer, even if only for nostalgia.
So, for whatever reason--honest business need, opening those old MacDraw files, or just for grins--you want to run Mac OS 9 (or even pre-OS 9) on your new Intel-based Mac. Apple says it can't be done (in fact their internal sales training on virtualization specifically states as much), but of course they're wrong. You can even run Mac OS 9 in Windows and Linux, for crying out loud.
Visit http://www.emaculation.com
Perhaps you're more interested in a drag & drop solution? I created a Mac OS X-ready version of SheepShaver/COI (Classic On Intel) that you can download at http://homepage.mac.com/jl
There you have it. A way to run Mac OS 9 on the latest and greatest Apple hardware. It will impress your friends, possibly astound the staff at the Apple Store, and it might just come in handy for some real work once in awhile. Who knows?