This image to the left is one of the truly most outstanding pictures I have seen of the sky. It shows the edge-on spiral galaxy NGC 5907, and it's surrounding by several loops of stars, the leftover remains of another galaxy eaten by NGC 5907.
I found this picture through a link from Pamela Gay's Star Stryder blog. She wrote an outstanding essay on galactic mergers, well worth a read. In fact, I'll try to link to it whenever I talk about mergers here on BA, because she covers a lot of ground and describes it very well (and not just because she links to my book).
In fact, if you don't have Pamela's blog on your reading list, you're missing out. When I get my sidebar here straightened out, count on me having her listed in my blogroll. She's a good friend, and a good writer.