Treesheets can already be used portably, but it requires reading and writing to the registry. It is freeware, is there any roadblock to make that portable?
Treesheets is "the ultimate replacement for spreadsheets, mind mappers, outliners, PIMs, text editors and small databases.
Suitable for any kind of data organization, such as Todo lists, calendars, project management, brainstorming, organizing ideas, planning, requirements gathering, presentation of information, etc.
It's like a spreadsheet, immediately familiar, but much more suitable for complex data because it's hierarchical.
It's like a mind mapper, but more organized and compact.
It's like an outliner, but in more than one dimension.
It's like a text editor, but with structure."