I'm sure it's the nice Mediterranean culture that attracts them there, and also of course the language. I can relate to that in so many respects. I love Mediterranean culture and the temperate climate you guys have over there.
I don't have any specific links to sites in Spain, but I was surprised to see an Italian site with a lot of nice t-girls from all over, most from Latin America (Brazil included).
They can be found here:
www.toptransitalia.com