StumbleUpon is not much good for games modding, but game fans sites and mapping should benefit a little from those tips.
The html for the blue box:
<div style=\"width: 360px; border: 1px solid #BBD9EE; padding: 4px; background: #FAFAFA; font-size: 12px;\"><img src=\"http://www.stumbleupon.com/images/stumble7.gif\" alt=\"StumbleUpon\" align=\"left\" style=\"margin: 1px 3px 6px 3px;\" /> If you like this THING, please <i>thumbs up</i> it, so more Stumblers can find it :) </div>
I used to have a php code for checking if StumbleUpon.com was the referral and making it show that box, but i can't find it atm. I'll have to find it for a site i'm working on, when i do i'll post it here.