Michell Engineering offers a rather shallow cone called "small tenderfeet". They are only about half an inch tall. Copy and paste this for a review.
www.audioreview.com/Michell,Small,Tenderfeet/PRD_117905_1590crx.aspx
www.audioreview.com/Michell,Small,Tenderfeet/PRD_117905_1590crx.aspx