The best place to start is the Expat Guide to Barcelona. It has a section on visas and Tarjeta de Residencia.

"The Tarjeta de Residencia Card (Residence Card) incorporates a NIE, personal details and a photograph/fingerprint. It is necessary for transactions where someone wants to see a proof of current physical address in Spain. This may be for formal services such as setting up a bank account, or at a video rental store. The Ministerio de Politica Territorial administrates the dispersion of permits.

All EU and EEA citizens and their family members have the right to live and work in Spain, but if they remain in Spain longer than three months, a registration certificate as an EU resident is required.
Non-EU/EEA Spouse and Dependent Family Members are legally registered partner and dependent family of an EU citizen in Spain are entitled to the same rights as an EU citizen to live in the country. Within three months of arrival, application must be made for an EU Family-member Residence Card (Tarjeta de Residencia de Familiar de Cuidadano de la Union). Non-EU/EEA Citizens staying in Spain for a period longer than three months must get a Residence Card (Tarjeta de Residencia) residency permit.

Documents Needed:
Current passport, plus copy
3 recent passport photos
Completed application form, plus 3 copies

A medical certificate may be necessary depending on country of origin and recent residency. In some cases, an employment contract, proof of financial stability, medical insurance, or proof of matriculation in an accredited school may be necessary.

The Tarjeta is valid for five years. Non-EU applicants are granted an initial Residencia for one year, which is usually extended to five years on renewal. "

Anyone have experience applying?