I think that more should be done to improve public transport in the outer suburbs. (I lived in Ferntree Gully for 15 years, and hence know how poor it is. I was one of the luckier ones, though, living within 10 minutes of a railway station.) Expecially now that gentrification is forcing low-income earners into the outer suburbs, where surviving without access to a car is difficult, a public transport system would be much needed.
<SPECULATION TYPE="CRACKPOT"> For one, Melbourne's commuter rail system has the fatal disadvantage of running only radially; i.e., in and out of the city. There are no lines circling the city, and to travel from one outer suburb to another, one has to go into the city centre and back out. The spur line from Huntingdale to Rowville could be a step in the right direction, being not far from the Belgrave line. Additionally, it could service Monash University, which has the distinction of being (a) Melbourne's largest university, and (b) in the middle of suburbia, half an hour's walk from the nearest railway station and wholly dependent on cars and bus services.
Secondly, extending the tram line to Knox City is an OK idea, though it is, once again, radial; a journey into the city by tram would take 2 hours or so. It could be extended into an outer-eastern tram network, with a tram going from Knox City to, say, Bayswater (and to the Rowville rail terminus in the other direction, if need be), linking two railway lines. And more lines could be added, running along the wide roads, and making the outer east more hospitable to the carless. </SPECULATION>