Virgin Mobile started selling MiFi modems. These devices allow you to create a mobile Hotspots so devices with Wireless card can connect to Internet over 3G (UMTS) or GSM networks.

Device has following advantages:

• Multiple devices can connect to Internet on the go.
• Device is battery powered and could be recharged using a standard USB cable.
• Devices with WiFi capability, but without 3G connection (such as Apple iPod) can now be connected to Internet from any place
• Other WiFi devices, like Skype or SIP hardware phones could be connected via 3G network

Device which is sold by Virgin is locked to Optus network, but you can purchase unlocked version of this device which is Huawei E5830 on eBay for approximately AU$120. Unlocked version is better if you travel outside Australia frequently, so you can connect to overseas mobile Internet providers just by purchasing their SIM card instead of buying another (probably, also locked) modem.