I currently have a SharePoint 2013 Web Application using Claims and FBA, once the user logs in I can see the ClaimsIdentity object, and in there is the Claims collection. How would I go about adding a claim such as country to the claims?
You'll have to write a custom claims provider and override the FillClaimsForEntity method (cf. http://msdn.microsoft.com/en-us/library/microsoft.sharepoint.administration.claims.spclaimprovider.fillclaimsforentity(v=office.15).aspx).
I hope this helps.