I’ve written a web part that provides a ‘newsticker’ for SharePoint, although it’ll actually query for news, documents, or anything else you can query for with the Content Query Web Part (CQWP). In fact, it’s just a configuration of the CQWP, which also uses jQuery for animation and stuff. Typically web sites use this for displaying news or announcements, but you can use it to query for any SharePoint content type(s), as you would with the Content Query Web Part.
The Content Query Ticker Web Part looks like this in operation…
It does require MOSS 2007, and you do need to enable the Publishing Infrastructure on your site collection.
For more details, see this page.