In the richfaces scrollable data table you may click-select rows (even multiple) and bind a selection object to your backing bean. I find that very neat...

there is a nice example on their live demo page http://livedemo.exadel.com/richfaces-demo/richfaces/scrollableDataTable.jsf?c=scrollableDataTable

It sort of takes them directly. It was some days ago I read that code but it workes something like this:

selection="#{dataTableScrollerBean.selection}"

gets/sets a Selection object. It contains a map with key/object to the rows that are selected. Hence, the takeSelection code iterates over this Selection object and just creates another list with selected items. Something like (psuedocode, all names made up):

public List<RowItems> takeSelection() {
   Map<Integer,RowItem> allItems = getItems();
   List<RowItems> selectedItems = new LinkedList<RowItems>();
   for(MapItem item: selection) {
      selectedItems.add(allItems.get(item.getKey()));
   }
   return selectedItems;
}