Try to get to the Irish Bar, The Connemara. Mention Eric Cantona and you might get a free drink...I say might.
Dress Code: Try and get in with an Eric Cantona mask!
Full every summer evening, and at night, cheap, it's a typicat spot for young pros and students living in the center
I am not sure of the name of this bar, but it is located just of Place du Parlement.
It is large, cave type bar that serves tasty drinks and played great jazz music when we were there.