I use it mostly to parse out the file names from a long file path. Example:

DECLARE @FilePath VARCHAR(100)

SET @FilePath = 'C:\Users\abcd\AppData\Local\Temp\Temp.txt'

SELECT REVERSE(LEFT ( REVERSE(@FilePath) , CHARINDEX('\',REVERSE(@FilePath))))

Instead of finding the last backslash throu string splitters, i used combination of functions along with REVERSE to do the task..