Most of the tools discussed in this page are FREE.
NetWrix Active Directory Change Reporter
NetWrix Active Directory Change Reporter is an Active Directory change auditing solution that tracks all changes made to Active Directory and Group Policy such as permission delegation and schema changes. The product automatically creates change audit reports and real-time alerts that show who changed what, when, and where for all changes in human-readable form without having to resolve complicated native identifiers
NetWrix Account Lockout Examiner Freeware
NetWrix Account Lockout Examiner is a completely free product designed for troubleshooting of account lockouts. Should an account lockout occur, the tool will alert the personnel in charge and provide a quick way for effective resolution. That means, if users or services start to experience a lockout issue, NetWrix Account Lockout Examiner will allow you to fix those issues immediately. After the account lockout has been detected and possible causes have been fixed, the account can be quickly unlocked or the password can be reset from the same console.
Free NTFS Permissions Analyzer for Active Directory
This free Permissions Analyzer for Active Directory allows you to achieve instantaneous visibility into user group permissions and get a complete hierarchical view of the effective permissions access rights for a specific file folder (NTFS) or share drive!
WindirStat
Very efficient tool for troubleshooting disk space related issues. You can exactly locate the files/folders that are occupying space on your server/desktop disk.
Windows user profile deletion tool (delprof2):
Delprof2 deletes inactive user profiles. If you want to reclaim disk space just run it without parameters and it will delete all profiles except your own and some special profiles needed by the operating system (like “Default”).
Delprof2 has additional filtering options: you might want to delete locally cached copies of roaming profiles only or delete only those profiles that have not been used in a specified number of days. Delprof2 does it all, both on the local system and remotely.