In Firefox 2.0 plus - Click on someone's Chicken coop expansion and probably elsewhere and you get this link:
Use the link to install farmville toolbar. When all done, go to farmville again and you get 25 FV cash. There are a few kinks. You will need to click at the top of the page to let Farmville install the toolbar. When it is installed, the intallation process doesn't see to go anywhere. You need to go back to your Farmville page. But there are really 25 Farmville Cash waiting in the giftbox.
No kidding. Get it while it lasts.