Well in terms of awesome and alternative-places for nightlife (i.e. laid back lounges, jazz bars...places decorated with abused baby dolls.), go upto Brunswick St. Fitzroy (and if you're in the mood to pick up some bargains a la discount outlets, check out Smith St. that runs parallel to it)...places like Black Pearl, The Bar With No Name, Night Cat..Bimbo's...
If you want the ol' school dive bar kinda jaunt...there's Cherry Bar (on AC/DC Lane I believe) where lots of famous musicians often go to hang out after their shows in Melb and Ding Dong Lounge (somewhere among the numerous little lanes and alleys within the CBD) which is part of a group of lounges around the world..i think there's one in NYC and London as well?
If you're thinking of doing daytrips outside Melbourne...I would highly recommend going down to Wilsons Promontory (the southern tip of the continent) if you haven't already, and another place you might have been already..The Grampians..
Sticking to the city...if you're interested in shopping..you can also check out the giant DFO's at the Southern Cross station..lots of outlet stores...but if you don't care so much for the price tag...there's always Toorak Road and Chapel St. down in South Yarra..
Oh and I think the Moomba Waterfest is happening soon too..so yeah, random stuff and fireworks on the Yarra...
you should check out this
website, they have lots of info on goin out and dining,etc.