IWSH

When executed, iwsh.wsf provides a command-line interface to evaluate and execute ad-hoc code. Enter expressions, and they are evaluated, or enter a blank line to toggle multiline statement entry. By default, the scripting engine used is VBScript, or JScript if the //job:jscript argument is specified. Press Ctrl+Z, then Enter to exit.

Generally, IWSH is good for testing language features

Interactive Windows Scripting Host [VBScript]
CBool("3")
True
CBool(Now)
True

IWSH is also good for complex mathematical calculations:

Interactive Windows Scripting Host [VBScript]
Enter
Enter statements, followed by a blank line to execute:
Function Secant(x)
Secant= 1/Cos(x)
End Function
Enter
Executed.
Secant(1)
1.85081571768093

One particularly handy use is as a date calculator, leveraging the date support in VBScript:

Interactive Windows Scripting Host [VBScript]
Date + 90
10/06/2005
#Dec 31# - #Oct 31#
55