I love the matrix view screensaver, but i can only look at Neo for so long before I wanna change the pics, and Jons_Collasius on UbuntuForums is the person with the solution.
He/She/It/Other says that you need to edit /usr/share/applications/screensavers/matrixview.desktop (I needed to sudo) so that it looks like this:
Comment=Assimilation of Matrix GL by Alex Zolotov (http://knoppix.ru/matrixgl.shtml) Ported to Linux by Tugrul Galatali – .
Exec=matrixview -r –image /path/to/your/pictures
I used a folder in my Dropbox folder for this so that i can have all of my boxen show the same awesome pics.