HI, Yes, I know several, ested by my friends when visiting:
Barcelona:
Kabul Youth Hostel , in Plaza Reial, just off the Ramblas. Great atmosphere but you wont have much rest!! good for the fun.
Gothic Point (
www.gothicpoint.com ): very original rooms, around 20€ but you need to rent linen. Cheaper: MAre de Deu de Montserrat, (IYHA) far appart but wondeful views. Not so convenient for clubbing.
MAdrid: highly recomm: LOS AMIGOS (
www.losamigoshostel.com) just opened but already very popular, 15€ with breakfast & linen included. Very helpful reception & great atmosphere, KITCHEN!! & so on, great for solo travellers.
Also Barbieri (BArbieri street, 15) and San fermin (sorry, donīt remember the address, but ask at the tourist info at airport or train station)
For traditional hostales, my friends also stay in Gala (Pza Sto Domingo,2)
Enjoy Madrid!