I may actually be insane.
Looks like someone has decided to abuse Apple's auto install feature in Dashboard. There's no real harm that can be done (I don't think widgets have the privileges to do damage... yet anyway ) but it can be very annoying and effectively break dashboard:
Full information (and the download) are available from the following address, however - not that it should need saying - Don't visit in Safari
You cannot get rid of zaptastic_evil without deleting it from ~/Library/Widgets/ and rebooting your computer. You cannot use your Dashboard until you delete it from ~/Library/Widgets/ and reboot your computer. Write that down if you're not clear on the concept, on a piece of paper, not a Dashboard sticky, because you won't be able to read it once you've installed this. Because Apple didn't actually give you a way to relaunch Dashboard without a reboot, though I suppose you could just kill the process. Certainly there is no user documentation for that.