If you can't get enough of WIkipedia founder Jimmy Wales' smiling face, pleading for your donations to keep everyone's favorite community knowledge base afloat, then you need the Jimmy Wales Chrome extension. With this little browser add-on, donation banners featuring Jimbo himself will follow you everywhere you go on the web.
I'm not sure why someone would install this on their personal machine instead of just donating to Wikipedia, unless they just really, really loved Jimmy Wales. On the other hand, installing it on public machines might be a sneaky way to get the word out about Wikipedia. You'd think the staring face of the site's founder would creep people out of donating, but Wikipedia's research actually shows the banners are super effective versus text-only versions...