Today I released a new tool for the community! ConfigMgr Add2Collection is a free tool that allows IT administrators and support staff to add resources to collections in ConfigMgr independently of the ConfigMgr console. It honors role-based access control (RBAC) to limit visibility of collections where appropriate. It can be used either on the Site Server or a remote workstation using PS remoting.
The tool includes a collection explorer so you can browse for collections, view collection details and current membership.
See more info here.