Josh Smith wants to find every installation of SQL Server Reporting Services on a machine:
This is one of those posts so I never have to google this again (one hopes). Here is the PS code to pull back a set of details about every SSRS instance installed on a server including the SSRS instance name, & the first URL port it is running on, the service name and the name of the report server database etc.
Click through for the Powershell script.