You may have to wait a bit yet, but according to a recent review response, from Chirag Mehta, on "Metadata Search" they are working on adding workflow rules and validation rules.
Chirag Mehta Hi Alex,
Thank you once again for your interest in "Metadata Search".
To make things easier for you, we have added the ability to search
Metadata Search App now supports searching inside Apex Triggers, Apex
Classes, Visualforce Pages or Visualforce Components. For e.g.,
Searching for "BillingCity__c" will find all metadata components along
with all Apex Triggers, Apex Classes, Visualforce Pages or Visualforce
Components containing "BillingCity__c”.
Do try out and Let us know your valuable feedback. We are now working
on adding support for workflows and validation rules, will keep you
posted once we are able to support same.
Need help? No Problem! Contact Us at [email protected]