I've been looking for an RSS feed 'ticker' for Ubuntu for a long time without much luck, until I found Snackr, which is also the first Adobe Air app i've found that I haven't immediately uninstalled! Being an Air app of course means it is cross-platform too. Amongst other features, you can set scroll speed, position, opacity, and set it to sync with Google Reader.
Screenshot on my main (dual monitor) desktop:
Screenshot of Snackr's horizontal arrangement my laptop: