I've had a couple of situations recently that caled for a scrolling text box smack in the middle of my HTML layout. Because the sites were running off Expression Engine for the CMS, and SEO for both sites very of primary importance, I couldn't use Flash. And rather than using some nasty IFRAME (I've just never gotten used to that thing), I found jScrollPane, a jQuery based solution.

jScrollPane can easily be skinned with CSS to integrate nicely into any design and work across every browser. Here are some simple examples.

I've also found the browser support to be perfect. For me that means IE 6+, Firefox 2+, Safari.

I use this on Derek Vreeland's site as well as the Advent Conspiracy site. As I said, the fall back solution, and the solution I would have used previous to happening upon jScrollPane, would have been to do this in Flash. While Flash has gotten better at font rendering and recently has received some SEO help, it's still not as easy as this solution.