This extension allows you to create templates for Contacts and Contributions.
Templates will pre-fill your "New Individual", "New Organization", and/or "New Contribution" screens with values you've pre-selected. This includes custom fields and tags/groups. Perhaps you have a regularly scheduled event that brings in new constituents that need the same "Source" field and are tagged/grouped the same way - this will cut down on repetitive data entry.
Follow the instructions to install extensions manually in the CiviCRM documentation.
Documentation for this extension is available on the CiviCRM documentation site.