Australia now has a government 2.0 taskforce.
AUD $2.45 million of funding to web 2.0-ify the Australian government.
Here's some ideas, to get you started:
CrimeTweet - A twitter like application, based on identi.ca, Google Maps API, and Zemanta.
Our local police force has someone publishing crimes on the front page of their website, which is also fed out to newspapers.
Why not provide an identi.ca client which lets you tweet about crimes?
Use a tool like Zemanta to linkify keywords, and google maps API to add an approximate geolocation (say, street level accurate). You add in structured data (RDFa?) too.
Effort? I'd peg it at 2 months to get it polished; and then it's a matter of getting police forces to use it.
Benefits: A much tighter integration with citizen police groups (neighbourhood watch), and the ability to do crime maps / analyze the data.
Idea 2: As above, but expand it out to neighbourhood watch people, give them easy tools to upload photos of minor crimes (ie, graffiti).
Idea 3: Stolen goods register, powered by Freebase.
You use a Freebase suggest control to help people tag consumer goods / get pictures of said goods, plus a bit of storage for serial numbers and descriptions.
You provide RSS feeds / emails to all local pawn shops, cash convertors, etc.