Useful links

Government offices:
Property Registry [Spanish]
Agencia Tributaria [Spanish]
Agencia Tributaria's page for nonresidents [English]
Spanish Notaries site [Spanish]

Spanish real estate sites:
Casa Home Search
Acsentra

Spanish architectural firms:
Lodaki Design Group

Expat sites:
Barcelona Tourist Guide
Expat Financial
expats.org.uk
Spain and Portugal for Visitors