I have a customer with a TON of workflows and custom fields. I needed to figure out everywhere that a field was used in the workflows. After doing some Poking around in the database I created a simple SQL statement that tells me everywhere the field is used. In this case I have a field on the opportunity that I want to find out all of the surrounding workflows that affect it.
So I ran this SQL against the database and entered the entity and attribute.
SELECT w.categoryname, w.name, w.statecodename, w.statuscodename FROM FilteredWorkflowDependency AS wd INNER JOIN FilteredWorkflow AS w ON wd.workflowid = w.workflowid WHERE (wd.dependententityname = 'opportunity') AND (wd.dependentattributename = 'hci_allpaymentsreceived')
I now know the two workflows that this field is used in and can go from there.