The busy beavers at deviantART have been hard at it.
In the last month or so over 110 new mail stamp icons have appeared, covering everything from celebrities to musicians such as Johnny Cash, Bob Dylan, ten rappers I’ve never heard of and Iron Maiden. Half-Life, Lost and the Citadel also get a look in.
Descriptions, a link and a sample of the contents in each set follow. (Hint: Read to the end if you are new to Hawk Wings for installation instructions.)
deviantART user hellhound has created three sets of replacement mail stamp icons.
The first set 
is a block buster, offering forty icons, including Jessica Alba, someone called Ambrosio, Eminem, three Elvis icons, Half-Life icons, Johnny Cash, Keira Knightly, Maggie Grace, Ray Charles and lots and lots of Scarlett Johansson:
The second set contains ten pieces of Iron Maiden artwork (album covers?):
His third set features thirty assorted celebrities — among them three Bob Dylan icons, Keeley, Lohan and Aguilera et al, two Veronicas icons and, of course, lots more Scarlett Johannson:
Another deviantART user karnakhan offers twenty more celebrities , five variations on each of four images, two of Elisha Cuthbert and two of Scarlett Johansson (who is going very well in the 2007 Mail stamp icon stakes):
Lastly, TheEnvyProject offers up ten rappers in two sets.
I’m jiggy wid it, but I don’t knows their names well enough to type them out. I think my younger brother may once have liked Tupac:
Some of these are PNG or ICO image files not ICNS icons. You will need to convert them using a tool like the excellent and free img2icns utility.
Changing Mail.app’s Dock icon is easy.
I’ve added them to the Hawk Wings Alternative Mail Stamps Icon list, which gets quite a boost out of this post and now contains 444 different icons.
The Rap Up icons are (from left to right, up to down): Chamillionaire, 2Pac, Rick Ross, Jadakiss & Dr. Dre.
Thanks, Ryan!