Sure. I got this from somewhere else on Reddit, so I can't take credit. It requires 36 images, and but I used 12(x3) here. The comments explain how it works pretty well. See my test sub for it in action: http://www.reddit.com/r/T01FR0EubG9n

/* 270 will need to be adjusted depending on the height of your rand image */ .side { position: absolute; top: 300px; right: 0; }

/* The height and width of all images must match. Change 228 and 300 to match
   your image dimensions. */
input[name=uh] ~ a:after, .user .login-required:after {
    position: absolute;
    top: 53px;
    right: 0;
    z-index: 0;
    width: 300px;
    height: 228px;
    border: 0;
 }

/* Name all your images rand followed by 0-9 and a-z, you can have 36 possible
   random images, feel free to reuse images if you have less than 36. For
   example, you could have 12 images repeated 3 times.                      */
input[name=uh][value^="0"] ~ a:after { content: url('%%bow1%%'); }
input[name=uh][value^="1"] ~ a:after { content: url('%%bow2%%'); }
input[name=uh][value^="2"] ~ a:after { content: url('%%bow3%%'); }
input[name=uh][value^="3"] ~ a:after { content: url('%%bow4%%'); }
input[name=uh][value^="4"] ~ a:after { content: url('%%bow5%%'); }
input[name=uh][value^="5"] ~ a:after { content: url('%%bow6%%'); }
input[name=uh][value^="6"] ~ a:after { content: url('%%bow7a%%'); }
input[name=uh][value^="7"] ~ a:after { content: url('%%bow8%%'); }
input[name=uh][value^="8"] ~ a:after { content: url('%%bow9%%'); }
input[name=uh][value^="9"] ~ a:after { content: url('%%bow10a%%'); }
input[name=uh][value^="a"] ~ a:after { content: url('%%bow11%%'); }
input[name=uh][value^="b"] ~ a:after { content: url('%%bow12%%'); }
input[name=uh][value^="c"] ~ a:after { content: url('%%bow1%%'); }
input[name=uh][value^="d"] ~ a:after { content: url('%%bow2%%'); }
input[name=uh][value^="e"] ~ a:after { content: url('%%bow3%%'); }
input[name=uh][value^="f"] ~ a:after { content: url('%%bow4%%'); }
input[name=uh][value^="g"] ~ a:after { content: url('%%bow5%%'); }
input[name=uh][value^="h"] ~ a:after { content: url('%%bow6%%'); }
input[name=uh][value^="i"] ~ a:after { content: url('%%bow7a%%'); }
input[name=uh][value^="j"] ~ a:after { content: url('%%bow8%%'); }
input[name=uh][value^="k"] ~ a:after { content: url('%%bow9%%'); }
input[name=uh][value^="l"] ~ a:after { content: url('%%bow10a%%'); }
input[name=uh][value^="m"] ~ a:after { content: url('%%bow11%%'); }
input[name=uh][value^="n"] ~ a:after { content: url('%%bow12%%'); }
input[name=uh][value^="o"] ~ a:after { content: url('%%bow1%%'); }
input[name=uh][value^="p"] ~ a:after { content: url('%%bow2%%'); }
input[name=uh][value^="q"] ~ a:after { content: url('%%bow3%%'); }
input[name=uh][value^="r"] ~ a:after { content: url('%%bow4%%'); }
input[name=uh][value^="s"] ~ a:after { content: url('%%bow5%%'); }
input[name=uh][value^="t"] ~ a:after { content: url('%%bow6%%'); }
input[name=uh][value^="u"] ~ a:after { content: url('%%bow7a%%'); }
input[name=uh][value^="v"] ~ a:after { content: url('%%bow8%%'); }
input[name=uh][value^="w"] ~ a:after { content: url('%%bow9%%'); }
input[name=uh][value^="x"] ~ a:after { content: url('%%bow10a%%'); }
input[name=uh][value^="y"] ~ a:after { content: url('%%bow11%%'); }
input[name=uh][value^="z"] ~ a:after { content: url('%%bow12%%'); }


/* Moves the username and bar to the top, may need adjustment depending on
   your other subreddit css. */
#header-bottom-right {
    position: absolute;
    right: 0;
    top: 19px;
    padding: 4px 4px 4px 7px;
    -moz-border-radius-topleft: 0;
    -webkit-border-top-left-radius: 0;
    border-top-left-radius: 0;
    -moz-border-radius-bottomleft: 7px;
    -webkit-border-bottom-left-radius: 7px;
    border-bottom-left-radius: 7px;
    line-height: 12px;
    height: 15px;
 }

/* Adjust the -228 to match the height of your image. Along with the 300 and
   228 to match the width and height of your image. At the end of your sidebar
   description create an H5 link to your subreddit homepage.
   Like this:  #####[Subreddit Name](http://reddit.com/r/SubredditName)       */
.side .usertext-body h5:last-of-type a {
    position: absolute;
    top: -228px;
    right: -5px;
    width: 300px;
    height: 228px;
    z-index: 100;
    border: 0;
    font-size: 0;
 }

/* HOW THIS ALL WORKS:

   Everytime you load the page there is an invisible form (input) that relates
   to the logout button which generates a long random letter-number combo. This
   code takes the first digit of that code and then displays a specific image
   dependent on the letter or number that was generated when the page loaded.
   Since the number comes from the logout button there are a few things to take
   in to consideration. Firstly, the random image that is created will log you
   out if you click on it. So part of this code repositions a link from the
   sidebar above the random image, so clicking on it will take you to the link
   instead of logging you out. The other is that if a user isn't logged in the
   link to logout won't exist, so neither will the random image. It only
   displays to users who are logged in. So we target the Login link for those users
   and put a static image there that is only visible to people not logged in. This
   would prevent the page from having an empty chunk above the sidebar for
   non-logged in viewers. The code for this is below.
*/

/* Pick your favorite of the random images to be the static one that loads for
   non-logged in users.*/
.user .login-required:after {
    content: url('%%bow1%%'); }