Portugal
In Portugal, there is a Fiscal Identificantion Number (with the Portuguese acronym NIF). Actually there are four main identification numbers: Identity Number,Driver License Number, Fiscal Number and Social Security Number. All three are mandatory. From recent years different cards: Identity Card,Fiscal Card,Social Security Card,Health Card and Voter's Card have gradually been merged into a single Citizen's Card or Cartão do Cidadão. This will be done until 2012.
Read more about this topic: National Identification Number