SharePointD2D.com posted a great tip about how to add a "Send Mail" option to the "Edit Document" menu.
http://msd2d.com/Content/Tip_viewitem_03NoAuth.aspx?id=a0000455-f180-4be7-867f-e2c9586e15a9§ion=SharePoint
SharePoint offers a standard dropdown menu, containing a number of actions. For example: View Properties, Edit Properties, Add to My Links. Custom actions can be added to this menu. This tip describes how you can add a “Send Mail” option to the menu, so that users can easily send links to the document.