Need to find some time to try it:
How to build cascading drop down lists in a parent child relationship, conduct lookup and filter is widely discussed, yet there are no much viable solutions to it.
SharePoint Cascaded Lookup[ http://www.sharepointboost.com/cascaded-lookup.html ] is a tool which helps users realize such requirement.
Here are part of its features:
1. Cross-site look up SharePoint lists in other sites Build Parent-Child Relationship by filtering SharePoint columns,
2.Filter looked-up column by Filter Column in the looked-up list,
3. Filter looked-up column by Parent Column in the Cascaded Lookup Column residing list,
4. Two-way conversion to default SharePoint Lookup Column type or SharePoint Cross-Site 5. Lookup Column type Support filtering multiple-values Cascaded Lookup Column.