PowerSploit is a collection of Microsoft PowerShell modules that can be used to aid penetration testers during all phases of an assessment. PowerSploit is comprised of the following modules and scripts:

Nishang is a framework and collection of scripts and payloads which enables usage of PowerShell for offensive security, penetration testing and red teaming. Nishang is useful during all phases of penetration testing.

YARA is a tool aimed at (but not limited to) helping malware researchers to identify and classify malware samples.
With YARA you can create descriptions of malware families (or whatever you want to describe) based on textual or binary patterns.
Each description, a.k.a rule, consists of a set of strings and a boolean expression which determine its logic.