I've searched and have not seen a Ultimate Mortal Kombat friendcodes list.
I know it's a bit dated, but I've been a fan of the series since the get-go, which was probably around the age of 9 for me.
Personally, I think it would be cool to have some sort of database for friendcodes for people for whatever games they've got (rather than scouring through the lengthy stickied thread), but meh.
Anyway, my friendcode is:
If you've got enough pints of blood left in you, come get some!
Mail me if you want to add me on either the Wii or the 360.