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, don´t 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!