Today’s Astronomy Picture of the Day is a beaut! The wee thumbnail here does it no justice at all. It shows Saturn’s moon Dione, Saturn’s rings and the shadows cast by the rings.
And if you’ve never visited Astronomy Picture of the Day then you should. There are thousands of gorgeous pictures archived, with a new picture each day.
What’s more, you don’t just have to visit the web page. There’s an unofficial RSS feed, or you can use any of various bits of software or Dashboard widgets. I used to use Railhead Design’s APOD Grabber (and still get his RSS feed, mainly for the Friday photos of his cat Uno), and have experimented with haym37’s widget (which didn’t work well for me).