This is a relations picker for Umbraco v8. The UI is identical to the Umbraco Content Picker - it just saves as a relation instead.
Once you have installed the package, go to Settings > Data Types (Developer > Data Types on v7) and create a new data type to use it. Remember to pick a relation type here.
Updated to Umbraco 8
Updated to target Umbraco 7.6. Older versions are no longer supported.
Updated to take on the new picker appearance introduced in 7.6.0
Show the parent name when viewing the child in a bidrectional relation