From Facebook Developer Wiki

Facebook Platform Best Practices: Naming and Branding Your Application

The name and brand you choose for your application are an important part of how users will view your application. Whether or not your application lives inside the Facebook frame, we recommend that you think about how you’d like to brand your application.

You may want a clean, minimal user interface similar to the Facebook site that users are already accustomed to (as long as you don’t confuse users about whether or not an application is a part of Facebook, which is against our Developer Terms of Service). You may want to build a strong separate brand that your users can easily recognize. You might want to extend the brand you’ve already established with your other products for your Facebook application.

Naming is a key part of your brand, and you can name your application just about anything you choose. Application names are surfaced in these places:

• The Applications menu.
• The title of your application profile box.
• The application directory, including indexing for search.
• Application settings pages for users who have added your application.

Multiple applications can have the same name. A user can differentiate between applications with the same name by taking a look at the application's About page in the Application Directory, which includes information about the application’s functionality, user engagement metrics, and developers.

Note that the URL suffix that references your canvas pages (e.g. apps.facebook.com/your_app) is unique, and doesn’t need to match your application name.

The most successful application naming schemes to date have been:

1. Original words.
2. Descriptions of application functionality.
3. Extensions of names of your existing products.

In general, the better your application’s name expresses its value, the more likely it is to attract users. Focus your application name on the value it adds in conjunction with Facebook, whether it’s the brand you’ve already established with your other products or the social value you offer your users by building on Facebook Platform.

Also note that the Facebook Developer Terms of Service place some restrictions on branding (for example, you cannot use the word “Face” in your application name or “Facebook” before the top-level domain in your URL), so you should focus on describing the added value your application provides inside the Facebook environment. (Of course, the Facebook Terms of Service applies the general rules of site content to prohibit names that are generally offensive, vulgar, racist, and so forth.) Read the Facebook Developer Terms of Service for specific information.

We also suggest that you devote a part of your design time to thinking about how best to communicate the value of your application to users. The possibilities are endless, but we’ve found that clarity is most important to users – they’re more likely to use your application if they understand its functionality and how it relates to Facebook.