The message box viewer gives an excellent overview of BizTalk solution including custom tweaks against some "less" documented features. This helped me diagnose an exceptionally high load after we created additional host instances where someone had actually increased biztalk polling interval (but hadn't documented this so it was unknown to me).

http://blogs.technet.com/jpierauc/archive/2007/11/13/msgboxviewer-9-20.aspx

-Jennifer Zouak