Common attributes of the project ideas are:
- A set or sets of records. Usually with a geographic coordinate
- Displaying the set on a map, given the bounds of the map and additional criteria
Wikis are great for crowdsoucing content creation. Wiki pages have an identifier in a single namespace and their content is free-form. A structured wiki could use tags for hierarchies of pages and a container/key/value structure as content. The document style datastores are an obvious choice for storage. The HTML for CRUD operations fall out of the content of the document itself.
Whats left is markup for query pages and pages that represent an aggregate of data. There are a variety of simplified markup languages for formatting text. If one were extended to build an HTML form, that would help with searches. Aggregating results needs a programming language.