Land Tax
As noted in What to do, a sufficiently high land value tax would prevent the kind of speculative withholding of land evident in the case of the Waltons building.
Brisbane had a 1989 Inquiry into land value rating led by Gordon Chalk which noted that: "a charge on the value of land encourages development and discourages the speculative withholding of vacant land from productive use".
A key recommendation of the 2010 Henry tax review was the implementation of a broad based land tax.
In a Darwin parallel to the Waltons building, the old Woolworths building on the corner of Smith and Knuckey Street in the Darwin CBD, owned by Kerry Manolas, has been empty since 2007 or before. Terry Roth, Director of Herron Todd White Property Valuation suggests a land value tax would fix such problems: "A land tax would encourage a more efficient use of land by the fact that people wouldn't be able to afford to have shops sitting vacant for as long as they do at the moment. They would have significantly more holding costs than they do now so would prefer to see it rented or used than stand vacant." (Note that a poster on skyscrapercity.com claimed that Woolworths is still paying rent on the site as of October 2011.)
Another family, the Wakils, owns 15 buildings in the Sydney CBD and Pyrmont, some of which have been empty since 1981. See Sydney's Mystery Empty Buildings, [dead link] Sydney's Empty Property Magnates, and Empty dwellings in a city desperate for places to live.