I like what Rebecca Blood has to say in The Weblog Handbook about "Targeted Serendipity" - that "weblogs attract regular readers precisely because they regularly point readers away." For example, I used to have a link to WWDN (before he became devoted to poker and his site went all fubar) BECAUSE of the things I found through his site.
ie: Buzznet - Image Hosting
and Joe & Monkey - Web Comic
When I find a site that reliably links to other funny/good things - I add it to my bookmarks. It's good to have a few (or more) sites you know will provide you with funny things...
I like Joe & Monkey and Get Fuzzy partly because of the Pop-Culture references. Joe & Monkey - The main character is Joe Banks (Joe vs the Volcano, Teenage Mutant Ninja Turtles... things I grew up with) and sometime something comes up and I'm like... Huh? And I go and look it up.
Sidenote: When I link to sites outside of my own website I always have them open in a new window. I do this because the majority of my links are within the text of my post (See above) and I want my readers to be able to click on the link - see what it's about and come back to finish what I've written. This is how I prefer other pages to be - I've gotten into the habbit of right clicking and opening all links in new window.