When a dataset 'high value' is, is determined by the degree of contribute the data to:
Transparancy
Legal duty
Cost Reduction
Target audience
Potential for reuse
For example
The G8 Open Data Charterhas fourteen categories determined as 'high value'. This list give a indication of potential high value datasets and its helpful for data owners for opening the most relevant and useful datasets.
Companies
Company/business register
Crime and Justice
Crime statistics, safety
Earth observation
Meteorological/weather, agriculture, forestry, fishing, and hunting
Education
List of schools; performance of schools, digital skills
Energy and Environment
Pollution levels, energy consumption
Finance and contracts
Transaction spend, contracts let, call for tender, future tenders, local budget, national budget (planned and spent)
Geospatial
Topography, postcodes, national maps, local maps
Global Development
Aid, food security, extractives, land
Government Accountability and Democracy
Government contact points, election results, legislation and statutes, salaries (pay scales), hospitality/gifts
Health
Prescription data, performance data
Science and Research
Genome data, research and educational activity, experiment results
Statistics
National Statistics, Census, infrastructure, wealth, skills
Social mobility and welfare
Housing, health insurance and unemployment benefits
Transport and Infrastructure
Public transport timetables, access points broadband penetration