This may be worth looking at http://michaeljswart.com/2011/05/when-to-use-blocked-processes-reports/ where it also links to http://www.sqlskills.com/BLOGS/PAUL/post/Wait-statistics-or-please-tell-me-where-it-hurts.aspx.

sys.dm_os_waiting_tasks will show lock resources and linking it to sys.dm_exec_requests will give you the database id.