"This utility provides functionality to analyze broken ArcMap document (MXD) files. Depending on the analysis, entities contained within the broken MXD file can be copied from the broken file into a new MXD file.
This utility is provided as is. Before using this utility you should always back up the broken MXD file, and if you choose an existing MXD file as the target, that file as well."
"Mxd Editor is a tool that allows you to inspect and fix broken layers in your map documents (.mxd files). It is based on the Eclipse RCP framework and leverages the arcobjects components provided by ArcGIS Engine and ArcGIS Server. The tool is provided with the ArcGIS Engine Java Developer Kit and ArcGIS Server Java SOC installations."
ArcMAP MXD Redirect Data Sources
"Allows users to fix broken data source path's in existing MXD documents. There are two methods offered in this tool.
1) Interactive - This method will search for all broken data source paths in the MXD and prompt the user on each one and the user has the option of selecting a new data source.
2) Search & Replace - This method is very powerful and will search for certain strings and replace those strings in the data source paths.
There are some similar tools out there, but nothing with a "search and replace" option. Hope this helps you out!!! Saved us a lot of time for simple shapefile and geodatabase based workspaces. "