One client used autocad. We re-built it in javascript/html, then added version contol and reports.

Another was version control for bom/assembly processes. They wanted a visual tool for showing the differences. Sort of like a diff tool, but all the files were shown instead of just two at a time. Also, who made the changes.

ERP features that always amaze: kit demand; click a button, get a colored report with charts; click a button, see who and when changes were made to a part/order/entry.