Whether you're out to watch the impalement of a screaming Bovine Burger in Barcelona or on a quiet trip to see
that special sweetie on Montera Street in Madrid, remember to leave the little lady at home and check out the traction action in these and other cities. 

If you find yourself Spain where the rain falls mainly on the Euskotren, you have many fine options.
The Euskotren, for example,  isn't a metro but it certainly looks like one. (see the ERS are these great Euskotren scans. ) The rolling stock of the FEVE also looks like Metro rolling stock, and FGC trains and the DMU's of the SFM on Mallorca are similar to RegioSprinters.

Confused by all these initials? Here's a brief rundown:

There are two national companies, RENFE and FEVE.

Then there are several nationally operated regional companies, such as FGC, Euskotren and FGV. For example, FGV is a regional service run by the province of Valencia. Euskotren serves the Bilbao metro area and surrounding areas, and is run by its provincial government.

The word metro is used loosely in Spain. In an effort to discover the elusive metro de Cadiz, I learned that the line, with an underground section in Cadiz, is part of RENFE but refrerred to locally as the metro. In Vadiz, an 8 km city tunnel
is also being built by RENFE.

Update 2010: FEVE is modifying an old 1970s tram to run on a hydrogen fuel cell. The tram-train will serve the towns of Ribadesella and Llovio by the end of the year. FEVE also plans to open similar lines in Cartagena - Los Nietos, Asturias, Galicia and Cantabria. The zero emissions trams will whisk passengers along the tracks at a breakneck speed of 25 kph.

Spanish train links
Trains of Catalunya includes interurbans, tramways and metros
Light Rail Atlas
Spain report

FEVE train in Santander

Bilbao Euskotren, looking a bit like a modernized Moscow Metro