Gian Carlo Mingati has created a jQuery News Ticker called liScroll which is very easy to use. It transforms any given unordered list into a scrolling News Ticker automatically as well. If you want your list to scroll faster or slower than the default value, modify the travelocity param. The scrolling automatically pauses when you mouse over it. If you would like to pull your news items from a xml file, You should check out his xml-based newsticker with fade in and out effect and xml-based newsticker scrolling effect as well.
Matt Berseth has created a CNN Style Scrolling Ticker with the Marquee Toolkit Control. It supports both left-to-right and right-to-left scrolling directions. You can easily apply a CSS class to the item when it is moused over. And also it support dynamically repopulating the marquee after it has finished scrolling.