I am not at my personal computer right now, but I usually have a picture of something find great in some way.
I used to have a funny comic my little sister made based on the Mr. Fredrickson from Up actually being in a retirement home and demented to the point of him making up the entire adventure we have witnessed. I will post it if I can find it again because it is pretty fucking hilarious. That chump is almost as talented as I am.
But the picture I have on my background right now is a picture of my Dad, Uncle, and thepropayne after we competed (and somehow placed?!) in a triathlon.
Just about any great memory or picture that someone has made for me has spent sometime on my desktop.
As for the shortcuts that I have......Pretty much picture the geekiest stuff you can. All of the Diablo games, all of the Fallout PC games, and about a thousand lab report documents for my Chemisty classes.
You know, I don't think I've set anything personal or sentimental on my desktop. The closest I've come is a picture of an egret in the Atchafalaya Basin.
Make sure to post your sister's comic strip when yo find it.