Filtered Lookup is an advanced field type for SharePoint (WSS and MOSS) that can be replacement for standard out-of-the-box Lookup column. It can be added to a list or a document library from SharePoint user interface or using a feature.

Move elements and locate them even when moved to other location in portal - including different library or site collection.

Related Items field type allows to link selected search results to a document or list item as a collection of permalinks or normal URLs.

Search Results Grid allows you to create dynamic registers or tables that displays information aggregated from entire portal.

Search Results Link allows to define document search criteria and sort order for search results. When opened returns first document in results set.