*Bars & Clubs by Neighborhood - I found this very cool website with loads of bars, discos, clubs in Madrid. It is only in Spanish but is a good reference for nightlife and clubbing here (http://anas.worldonline.es/wonder3f/indicez.html) - Website in Spanish.
*LaNetro Madrid "Marcha" Pages - Hands down the ultimate website for the Bar/Club/Disco/Live Music/Party searcher. In Spanish only but easy to navigate even of you are an amateur, this is the Madrid "Cervecerías" (Beer Houses), "Copas" (Drinks) and "Discotecas" (Discos) section of the impressive LaNetro.com Spain city guides. Hint, after choosing your poison ("Cervecerías", "Copas" or "Discotecas" ) when it says "Elige zona", "centro" is central Madrid). (http://madrid.lanetro.com/guia/sitios/index.cfm?identificador=1) - Website in Spanish (if they translated this bad boy into English they would be dangerous).
*La Noche Castiza - What about diving into the best essence-scenarios in the Madrid Chulo? (not massive tourists allowed) tabernas, mesones, live events, música de la "movida", chulerio y casta (words that you,ll fully understand the day after). (www.myworst.com\nochecastiza\came.htm) - Website in English.
Clubs/Discos/Bars