One of the beauties of building social networks with well developed CMSes with lots of contributed modules is it resembles Legos more than churning out thousands of lines of code. Essential to this is educating User Experience designers and customers to the necessity for flexibility. Better to leverage other’s work and have something better sooner and cheaper than to make it all from scratch.
Along with modules come APIs. In short, if someone else built a site that does what you need, do rebuild it – hook into their site. For those not technically proficient, when you build a site and want to allow another site to hook into it, you wrap the site in an API. You can do this so you don’t have to rebuild all your functionality when you build a mobile app. You can also expose your functionality and data to partners or the public. APIs can provide you with weather, currency rates, stock information, news headlines, video listings, etc.
When you plan a site keep in mind a little flexibility will allow you to leverage more modules and APIs, getting you to market faster and cheaper. Having UX designers who know the industry and platform will help this a lot.
(This was originally on InteractiveQA.com)