I use Digsby as my instant messenger client. A couple minutes ago, I received an update which set ads to display in the conversation windows by default. I immediately decided I'd try to figure out how to remove the ads, or switch back to Pidgin, the free open source client. Turns out it was simple to turn off the ads. When you're done, you'll need to reopen your conversation windows to see the changes.
From the Buddy List window:
- Tools -> Preferences
- Uncheck "Support Digsby development by showing an ad in the IM window"