Now days web development is building off APIs as a third party app. Most of the mainstream social networking brands include a working API and documentation segment right on their website. Plus there are tons of free wrapper classes on Github written in all the major back-end programming languages.
Developers should feel comfortable working with these types of code libraries as they are growing in demand. Using the OAuth system you can quickly build up a userbase from many of these applications. I’ve listed below just a few references to popular online APIs and their full documentation.
Twitter API
Digg API
CloudApp API
Instagr.am API
eBay API
Foursquare API
Dribbble API
Github API
Take advantage of these resources on new projects whenever possible. The Web is becoming more connected and users are always flocking to the next big app. You can recruit thousands more dedicated members to your app when your visitors don’t need to register a whole new account and can instead signup directly through Twitter or Facebook.