I think there is an opportunity for a website to collate and share heuristics. The content of this website would be crowdsourced with submissions of heuristics from the community. Submissions could be up-voted or down-voted, and an average result available as the best heuristic (e.g. a vote-weighted average).
For each heuristic, the following could be submitted:
- average (mean)
- standard deviation
- other common values
The descriptive statistics that across submissions would need to be relevant to the underlying data, e.g. the mean mean, the maximum maximum, etc.
In addition to the above, modifying factors such as location, time, etc could be applied. For example, it might be the case that a particular heuristic has varied over the course of human history.
Another useful feature for the site would be unit conversion, for example converting meters into feet, or between currencies (using up-to-date rates, or relevant historic rates).