Rapid in the sense that I haven’t taken the time to think these through, but they present interesting possibilities.
Marginal land valuation. Apply a marginal tax structure to land value. Value the land as you normally would, but every dollar of value between (e.g.) $100,000 and $200,000 is reduced by 20%, every dollar from $200,001 to $500,000 is reduced by 75%, etc. There would be an estimated market land value derived in the current fashion, but this marginal valuation structure would then be applied and reduce it to its final value, which would then be used for determining rent, taxes, prices, and so on.
This has the advantage of removing the incentive that many cities have for raising land values in order to increase revenue and it could be used to clamp down on speculation and highly inflationary real estate.
Money IDs. Every cent should have a unique digital ID associated with it, possibly allowing it to be tracked through a blockchain or similar technology. The system would be able to compare every cent to every other cent and prevent fake money from being created. Could track money across borders, even across corporations, households, etc. This might just be me reinventing a tiny part of blockchain/bitcoin technology.