Deadlinks is a common problem for many pages. Not only that, people try to sneak into some pages where they aren’t supposed to be and so on. The 404 page is viewed more often than not and why not make it look nice? Smashing Magazine has gathered 40 nice looking 404 pages that makes your wrong step worth the while. Thanx to IDG for spotting this article, it sure is nice to check them out 
Might aswell add Dramatens 404 page cause it’s not in the article and it sure is worth a look
ps. I made dramaten.se during my time @ creuna. And the person behind the 404 page is Fredric Marcus.