well, it may be a bit harder than it was in weimar, but it is not imposible at all. i even believe it to be a task much more easier than finding a nice room in cities like munich or hamburg.

it took me 3 days to find something nice and as a handy side effect i got to know the basic structure of barcelona on my journeys.
a website that turned out to be realy helpfull is
www.habitagejove.com

on the other hand it was impossible to find somthing in adwanced when i was still in germany. long term planing does not seem to be in favourite of some spanish people, at least not, when it comes to renting a room. every time i asked if i could visit somthing the next week or so i got a: ¿eres
aqui? ¡llamas commo eres aqui en barcelona!
but the better this way. i don't like planing in advance much either.