Friday nights, north sydney will be pretty quiet, sat night there is a VIP Clubs night @ greenwood with DJ's, however tickets required so don't bother.. Apart from that, just go into the city.. Depends on what music you want.. Just bars and pubs, plenty round the rocks, up george street.. Club/Bars.. goto the cross or chinese laundry.. Dance/trance - well ferry corsten is playing at Sublime this weekend.. so that'd be a good draw card..
North sydney is good for a quiet beer, and if your already in milson's point, just train/cab it to the rocks.. Otherwise hook up with some SAU people and get them to take you somewhere..