I want to know in what programming language(s) is written a particular piece of software (for instance the Skype client or the Tomcat server).
While this information can usually be found by inspecting binaries with specialized pattern matching, it requires a lot of time and experience. For instance, distinguishing compiled binaries generated from C and C++ is very difficult when you don't have the source code, but not impossible.
Is there a database where this information is gathered?
It could be a collaborative database, possibly using bots to find and inspect binaries. It should contain open source software as well as proprietary software.
As an example, Github provides this information for projects hosted on their servers, for instance OpenOffice: