Add to favorites icon, how can i do it in my website?

How can I customize the icon of my website when the user adds my site to his favorites folder? IN the case of kirupa.com, the yellow/gold fruit (peach fruit, whatever it is) or the red [FONT=Palatino Linotype][SIZE=4][COLOR=red]Y![/COLOR][/SIZE][/FONT] in yahoo.

Thanks for sharing any help.

Thank you everyone. I have already done your suggestions but I never replied that I resolved it… with your help. Again, thanks a lot.