There isn’t an official guide on how to submit your app to Facebook’s directory, so here’s what I’ve found after going through the process several times.
You don’t have to submit your app to the directory. I never did for Defrag Connector, since it was distributed directly by the conference promoter, and wouldn’t have been helpful to the general public anyway. The strength of the directory is that it gives you access to the early-adopters, people who are actively looking for a new app to try. What you want long-term is an app that’s viral, so friends spread it to their friends to reach a much wider audience, but the directory is a good way to start the ball rolling.
In preparation for submission, you need to go to your Developer application and click on My Applications. Below each of your apps is an ‘Edit about page’ link. This is where you can provide a short description, a screenshot, and importantly, set the two directory categories you want your app to appear in. I’ve got no statistics to back this up, but it seems like "Just for Fun" is one of the most popular categories, so I’d recommend that if possible.
Next, make sure your app has an icon, by going to ‘Edit Settings’ for your application. Even though the icon is part of the optional fields section, Event Connector was initially rejected for not having one.
Once you’ve filled out all the information on those pages, you can click on "Submit Application" to the right of your app. There, you’ll need to fill out another description, and supply a larger icon for the directory listing. Once you’ve done that, your app is almost ready to be submitted.
The final hurdle is making sure you have enough users. You need a minimum of five to demonstrate you’ve been testing your app, and that you can personally persuade five people to use it. Hit up your friends and get them to give it a test run, and let you know what they think.
Once you’ve met all those conditions, you can submit the app for review. I’ve found it’s taken me two to three days, and as far as I can tell the inspection is fairly perfunctory. I can’t imagine it’s a sought-after job reviewing the apps, and I’ve had a spotty experience with the quality of the examination.
I submitted Event Connector four times in total before it was accepted. The first rejection was for the lack of an icon, which I fixed, but then the next two were random and confusing, claiming that my app had no content, and then that it violated the ToS because it gave access to secret events. Since there was little information in the rejections, and after research I couldn’t reproduce the problems, I resubmitted the app unchanged both times, and it was eventually accepted. Unlike the Firefox directory, there’s no two-way communication between the reviewers and the app developers, so I wasn’t able to get any additional guidance.
Once you’re in, you should get an immediate spike in the number of users, as the app shows up in the ‘Just added’ section of the directory. Then, I’d expect a steady flow of users, the size depending on the categories and appeal of your app. Hopefully you can gather a good base to build on with some viral distribution.
Funhouse Photo User Count: 1,697 total, 76 active. Still ticking upward, with fairly slow growth.
Event Connector User Count: 67 total, 6 active. I’m getting the Facebook equivalent of cosmic background radiation, in terms of new users through the directory. Still an uphill battle winning a new conference.