Mac: Retickr is a free program that generates a personalised news ticker on your desktop using multiple sources, including RSS feeds, social media and even email.
Unfortunately, there isn't a feature to import your own OPML files or login with a Google Reader account at the moment, but you can manually select and create your own custom feed from a large pre-picked list. If that sounds like too much work, you can use the built in setup wizard to help cater your choices by news type, then add or delete feeds as you go along. There are multiple playlists available as well, so you can change up the type of news to suit your mood throughout the day.
For the social among you, Retickr can take your Twitter or Facebook account and integrate shared links into your feed or distribute news to either account directly from the application. It has a lot in common with the previously featured Snackr, but the social integration and low memory usage makes it a step above for anyone looking for a news ticker for OS X.