Pretty straightforward. Allow players to craft custom dog-tags.

Its nothing amazing or game changing I know but it would be a fun little RP item or just something to wear around so that if someone stumbles across your body they know who you were as they were intended to be used.
To create them I'd recommend making an NPC in town or perhaps a talking dog-tag printer/computer in Sierra or Mariposa that when supplied with metal parts will ask the player for a name. Us the "Say" function and print your name and a second later you got yourself a custom dogtag with your name. As for the D.O.B or Date of Birth you can ether fill that out or it can be randomized.
It shouldn't be that hard to implement and its not ground-breaking or amazing but it would be fun for role-play or for identification or just to wear around town when idling.
Feel Free to Call Bullshit or give suggestions. Try to avoid going "totally fail u noob learn2play totally gayz"