If you're tired of the generic font Facebook uses for its main page, you can use one of several applications to change up the fonts and make your Facebook experience more interesting. Currently no application exists that allows you to unilaterally change every font you see on your main page, but you can use multiple applications to modify the fonts of your wall posts and status updates. Then, when these appear in your main page, the font will be changed to the one you used.
Use the Font General application to post your Facebook status in a different font. After using it, your Facebook status will appear on the main page in the font you selected. Note that it will appear in a normal font to most of your Facebook friends -- unless they also have Font General installed.
Use the Fontself application to change the font on your wall posts or in Facebook chat. When you use Fontself, you also have access to a variety of different emoticons and the ability to add text bubbles to your Facebook photos. As of the date of publication, Fontself is free to all Facebook users.
Use Font Changer, another free application developed for use with Facebook. The Font Changer application allows you to write on someone's wall using a different font than the standard Facebook font. If the wall post appears on your main page, you'll see it in the font you used.