Most of the examples you will find are using a simple text / CSV file as input but you can make it work with an XML as well. PowerShell has great support to read XMLs.
I am trying to come up with ideas. example what do you think organisations want other than reboot time? or disk space? I want to add info on servers…anything that might be useful to the system administrator.
I think make and model of the machine, serial number, CPU counts (sockets and logical processors) and model, RAM, disk space (especially tracking growth), IP information, OS version plus service pack, domain/workgroup membership, OS install date, local admin group membership and many more are useful for system administrators.