Ever wondered whether an instance of SQL is hosted on a virtual or physical server? This query will tell you:

SELECT
CASE virtual_machine_type
WHEN 1 THEN 'VIRTUAL'
ELSE 'PHYSICAL'
END as [ServerType]
from sys.dm_os_sys_info

You can also determine whether your server is clustered or not via T-SQL:

SELECT
CASE SERVERPROPERTY ('IsClustered')
WHEN 1 THEN 'YES' WHEN 0
THEN 'NO'
END as [CLUSTERED]

These are just a few of the queries I run when I am handed over a server that I have not been responsible for. You can see more of these queries in this post.