Skype has launched an App Directory for third-party applications integrated with Skype’s telephony service. It’s not much to look at now besides a handful of natural use cases. But as Skype’s footprint grows, the platform and the directory have real potential to grow with it.

Are you a Skype user who’s looking for a voice-and-video call recorder, a desktop sharing tool, integration with Outlook, or a free app for sending faxes? No longer need you turn to Google and evaluate apps in the wild, without easy comparison shopping, helpful category distinctions or customer reviews. Like a caveman.

But Skype’s App Directory is currently limited in small yet important ways:

• There are only 20 or so apps at the moment, which isn’t exactly the whole Skype ecosystem. The popular call recorder I use isn’t in there, for example. That number, though, should grow over time.
• Unlike the Apple, Amazon or Android app stores, Skype’s is really a directory, not a store. You can’t purchase the apps through Skype, but are routed to the developers’ individual sites.

  The best analog might be Dropbox’s Apps site, which likewise links out. But unlike Dropbox, Skype has a robust payment-and-credits system to handle its own services. Even though Skype isn’t owned by eBay any more, Skype and PayPal are still pretty well-integrated. Handling payments, refunds and information is a real service Skype could offer both its customers and developers. Not doing it doesn’t make much sense.

Some reasons Skype’s not going the Apple/Amazon/Android route:

• It keeps developers happy. They get full access to user and billing information, and users who are tied to them as much as Skype.
• The system’s a lot easier to scale if you don’t have to worry about handling payments, both in terms of approving apps and managing the backend.
• Skype doesn’t want to use PayPal or credit cards or anything else, but would rather wait until the Microsoft purchase is approved to roll out a 2.0 store using Microsoft’s own payment system.

Whatever the reasons, these limitations are why I call Skype’s a “junior” app platform. It’s still one that’s worth watching. That little platform might grow up in a big hurry.