Google has a dedicated section on their website related to Transparency Report. This is where they disclose all the requests made by governments and businesses around the world related to user information, copyright infringement and content that break the local laws and regulations.
Twitter has now released their own Transparency Report. There is no dedicated section for it yet but you can look at the data in their blog post.
Twitter spoke about the data released today:
One of our goals is to grow Twitter in a way that makes us proud. This ideal informs many of our policies and guides us in making difficult decisions. One example is our long-standing policy to proactively notify users of requests for their account information unless we’re prohibited by law; another example is transmitting DMCA takedown notices and requests to withhold content to Chilling Effects. These policies help inform people, increase awareness and hold all involved parties––including ourselves––more accountable; the release of our first Transparency Report aims to further these ambitions.