I realise visiting Sydney Harbour may not be feasible for most of you, but on the off chance it is, you should swing by Cockatoo Island and check out the real, working Halo Warthog that'll be sitting there this weekend.
It's the same Warthog that featured in Neil Blomkamp's ill-fated Halo short film, and was built by New Zealand special effects maestros WETA, the team behind Lord of the Rings.
These days, it's on promotion duties for Halo: ODST, hence the public display. If you've never been out there, just grab a ferry from Circular Quay; it shouldn't take you too long. Be a nice day out if you bring a picnic basket and some Halo action figures.
Cockatoo Island and the Warthog [Xbox Australia]