Data object renderers that include a SelectedItemIndex property can be used to reference data as described in
THIS article.
So far I've not discovered any way to extract data using renderers that don't include SelectedItemIndex.
If you must use something without SelectedItemIndex (like a table) for display, you should be able to also include a hidden renderer (like a dropdownmenu) that references the same data source and gets passed the table's selectedRowIndex. With the two properly linked, you should be able to extract identicle info from the hidden renderer as is displayed in the visible rederer.
This may not work with Data Sources dynamically updated by the server. Haven't tested it, but I suspect the hidden object wouldn't update properly when the Data Source values change.