My first experience with Pixel & Tonic came with their use of plugins for the popular CMS solution Expression Engine. I used this to build and oversee applications for a number of touch screens running in a tourist space in California. This included the use of their Assets plugin, Field Pack and Matrix plugin.
Every now and again we put together a Facebook tab to promote various campaigns across various countries around the world. With the introduction of Facebook's business manager we are starting to properly localise our applications so we can use one application that handles multiple localisations with one Facebook developer application. Facebook passes two pieces of data via its signed request that we can use to achieve this. The country that the page is being viewed from and the users language that they select with they initially sign up. This provides us with enough information to appropriately display content based on their region. When we localise tab applications we normally use an XML document to hold all the content on the page and links to images etc... This allows us to pass on the XML document to people in the office so that it can be populated with the locale content accordingly. Obviously this can be achieved in other ways such as localised through a PHP page or different localised database tables.
Slack is a collaboration tool that allows teams to work closely together. We setup Slack recently after it became apparent that we needed to deeply integrate the service into our work flow. It also has some great little tools for developers like creating text and code snippets. You can even create posts straight out of the entry box!