Once or twice month, someone posts a forum question: "How do I include hyperlinks to URL’s that are clickable from a SharePoint Designer email?"

Presented without further comment:  (well, actually there is further comment after the image):

Becky Isserman follows up with a helpful explanation on how to embed a link to an item in the email: http://www.sharepointblogs.com/mosslover/archive/2007/11/20/addition-to-paul-galvin-s-post-about-sending-an-e-mail-with-hyperlinks-in-spd.aspx