select p.object_id, object_name=object_name(p.object_id), p.index_id, buffer_pages=count(*) from
sys.allocation_units a, sys.dm_os_buffer_descriptors b, sys.partitions p where
a.allocation_unit_id=b.allocation_unit_id and a.container_id=p.hobt_id and b.database_id=db_id() group by p.object_id,p.index_id order by buffer_pages desc