I'm exhausted and have more travel coming up this week so I need to get to bed. But I can't go without wishing you a happy Saint Jordi day and sharing this most lovely Catalan holiday. So here's the short version:
Who: Sant Jordi is the patron saint of Catalonia, the Catalan equivalent of Saint George. 
What: Equivalent to Valentine's day, boys give roses (from the dragon blood), girls give books (Shakespeare and Cervantes both died on April 23, 1616). Roses are sold on almost every corner throughout the city, there are also special Saint Jordi book sales. All of the sale tables are covered in the Catalan flag. They're even set up in the airport.
When: April 23, also international book day
Where: Catalonia. Not celebrated in the rest of Spain.
Why: When Saint Jordi killed the dragon a rose grew from the spilled blood. 
Picture
Saint Jordi Day...notice the striped Catalan flag.
A few other things:
1) I had the chance to see the start of Feria 2012 in Sevilla, Spain. It was THE most beautiful display of horseflesh I have EVER seen. I took about a billion pictures and will post them here soon.
2) Below is the Spanish flag for comparison to the Catalan flag (in the picture above and in the last post). Pay close attention when you visit Barcelona or other parts of Catalonia...you will hardly ever see the Spanish flag flying, the striped Catalan flag is EVERYWHERE. You can find the Spanish flag, along side the Catalan and EU flags at the airport. 
Picture
The Spanish flag.