The information below are meant to be the 3G APN settings reference for anyone who uses Android mobile phones such as HTC Dream G1, HTC Magic G2 in Australia and New Zealand.

To change your APN setting in your Android device, on the home screen, press Menu -> Settings -> Wireless & networks -> Mobile networks -> Access Point Names -> Press Menu and add New APN

Disclaimer: The information below are collected and compiled from other web sites. It is subject to change by the network operator and may not always be correct. Please let us know if any of these are incorrect through our forum.

Australia mobile network

Optus (900/2100Mhz)

Contract APN: yesinternet
Username: (blank)
Password: (blank)
DNS: 202.139.83.3, 192.65.91.129
MCC: 505
MNC: 02

MMS
APN: mms
Username: (blank)
Password: (blank)
MMSC: mmsc.optus.com.au:8002
Proxy: 61.88.190.10:8070

Virgin Mobile (900/2100Mhz Optus network)

APN: VirginInternet
Username: Guest
Password: Guest
DNS: 61.88.88.88
MCC: 505
MNC: 02

(Inserting Virgin Mobile Broadband only sim will into Android phone will NOT connect to the 3G data network. We believe it is the lack of PAP authentication in Android, please contact us if you figured out to make it work.)

APN (BYO broadband): VirginBroadband
Username: (blank)
Password: (blank)
MCC: 505
MNC: 02

Vodafone Australia (850/900/2100Mhz)

APN: live.vodafone.com
Alternative APN: vfinternet.au (If you uses vfinternet.au, you may not receive free features included in your plan, for example if you are entitled to free unlimited facebook data, you will not get it if you uses vfinternet.au whereas if he uses live.vodafone.com, he will receive it as entitled.)
Username: (blank), Guest
Password: (blank), Guest
DNS: 192.189.54.33, 210.80.58.3
MCC: 505
MNC: 03

(Inserting Vodafone Broadband only sim will into Android phone will allow you to browse the internet using these settings.)

MMS
MMSC: pxt.vodafone.net.au/pxtsend
Proxy: 10.202.2.60:8080
APN: live.vodafone.com

Lebara Mobile (850/900/2100Mhz Vodafone network)

APN: purtona.net
Username: .
Password: .
MCC: 505
MNC: 03

Note: the dot above is the username and password. At the time of writing, Lebara charges 10c/MB to connect to their 3G/GPRS network.

Lebara mobile is currently one of the cheapest provider for casual internet use for using Google map for GPS, etc.

Telstra (850/2100Mhz)

3G/EDGE/GPRS
APN: telstra.iph
Username: (blank)
Password: (blank)
MCC: 505
MNC: 01

GPRS APN: - telstra.internet
Username: - (blank), guest
Password: - (blank), guest
DNS: 139.130.4.4, 203.50.2.71

3G data bundle: - telstra.datapack
Username: - (blank)
Password: - telstra
DNS: 139.130.4.4, 203.50.2.71

3G pay by time: - telstra.pcpack
Username: - (blank)
Password: - telstra
DNS: 139.130.4.4, 203.50.2.71

3G prepay: - telstra.wap
Username: - (blank)
Password: - telstra
DNS: 139.130.4.4, 203.50.2.71

Three (850/2100 Mhz)

APN: 3netaccess
Will give you public IP which means you have direct access to Internet, someone can connect to you and you can do port forwarding. Which also means you cannot access Planet3 with your browser.
Username: (blank), guest, a
Password: (blank), guest, a
DNS: 202.124.68.130, 202.124.76.66
MCC: 505
MNC: 06

APN: 3services
Will give you a private IP (using NAT), so you will not be able to forward ports or get direct access to Internet (which means someone cannot connect to you if you need to run P2P or a server), but you will be able to access Planet3 with your browser.
Username: (blank), guest, a
Password: (blank), guest, a
DNS: 202.124.68.130, 202.124.76.66

APN: 3service
No access to internet, internal 3 network only, ie: Planet3, 3 Web mail, etc.
Username: (blank), guest, a
Password: (blank), guest, a
DNS: 202.124.68.130, 202.124.76.66

More explanations can be found here and here.

New Zealand mobile network

Vodafone New Zealand (900/2100Mhz)

APN: live.vodafone.com
Username: (blank), guest
Password: (blank), guest
DNS: 202.20.93.10, 203.97.191.189
MCC: 530
MNC: 01

MMS
MMSC: http://pxt.vodafone.net.nz/pxtsend
Proxy: 172.030.038.003:8080

Telecom New Zealand (850/2100Mhz)

APN: internet.telecom.co.nz
Username: (blank)
Password: (blank)

Other overseas carriers

You can find APN settings for other overseas mobile carries from modmyi, unlocks, Ross Barkman and other web sites. MCC/MNC information can be found in wikipedia.