You can search under milongas by the day and
barrio at TANGODATA.
The hard copy publication B.A. Tango includes the Guia Trimestral which
has a current listing of all the milongas in the capital and province of
BsAs. But Tito Palumbo, the editor, doesn't allow anyone to copy it in
whole or in part. Rightly so. He works hard at compiling the information.
And he doesn't have a website with the information.