Mixmag replies:
XOYO, The Nest, Phonox, The Printworks (opens Feb), fabric, Corsica Studios, LWE events at Tobacco Dock and Village Underground.
London is famous for its club scene and it's a great place for electronic music.
I would recommend Phonox (personally my favorite), XOYO, Village Underground, Fabric. Fabric recently reopened and now has very strict security measures, making club entrance look more like an airport, but it's still worth a visit.
I'm surprised no one has mentioned Ministry of Sound - just five minute walk from Elephant and Castle.
Obviously Fabric, XOYO, Village Underground etc.