I recently was in Singapore and have to say the EZ-Link card system is very impressive.
I believe its still early days but there are about 10,000 places to use the card, according to their website!
http://www.ezlink.com.sg/index.php
The fare structuring is excellent. Its distance based so, for instance, going to the Jurong Bird Park from Town Hall MRT station would see something like a S$1.10 fare deducted for the train ride. At the interchange station, hop on the connecting bus and swipe on. Swipe off at the Bird Park stop and a further 9 cents is deducted to have the correct fare for the total distance.
This is a very fair system, requiring people to pay for exactly how far they travel and not requiring someone to pay a large flagfall for a very short trip whilst a longer traveller will pay the same fare.
It requires intelligent smartcard software. Unlike our dumbed down, struggling to cope with 2 zones Myki.
I have been using Ez-link for 8 years without any problem at all from the start. It is disappointing that for something introduced 8 years later, you still have to take your Myki out of your wallet to touch on when there is any other random RFID card present. And having written to Myki 5 times about being overcharged, no matter how much reason there is in my head I just feel very exasperated (most of the time, Myki failed to understand the simple concept of a weekend $3 cap). Better still, I have actually managed to touch a Myki reader on a tram Out of Service!

Interestingly I have been charged a Zone 2-only fare after touching on and off several Zone 1-only tram routes and many of these trams have their Myki consoles set permanently on some tram stop on Plenty Road. So far most other Zone 1-only trams have their consoles set on Spencer/Lonsdale Streets.
The full distance-based fares in Singapore is a new fare structure introduced in 2010, I haven't been able to use it yet being stuck here for the summer. It used to be distance-based within a single mode of transport with transfer rebates where you get a discount transferring from bus-bus or bus-train. However they did screw up big time with the switchover by calculating and programming the distance between bus stops wrongly, overcharging many people in the process.

At least you could get a refund automatically if you have been overcharged just by placing the card on any ticketing machine, no forms to fill out at all.
I think Melbourne's 2-Zone system really needs to be rethinked, why not take London's approach, doesn't have to take a full distance-based system but at least make it more graded and hence fairer. I don't think it will make public transport fares more expensive across the board, though it will probably make a number of people unhappy (read: those who used to be in Zone 3).
Something that I really don't get is Price of Zone 1+2=Price of Zone 1+Price of Zone 2. So other than "having a single valid ticket for the entire journey", what is the point of the Zone 1+2 Myki product if it doesn't provide any other advantages?
Just a quick question, not sure if this has been answered before, but are tram ticket inspectors equipped with readers that can check your myki to see if you have touched on?
Yes I have had my Myki checked by Yarra Trams AOs very recently. However I believe they are more interested importantly in whether you have an active valid Myki product.