Sharing:

• similar to permallink - button for 'share link' which can then be passed to another
• Can share single notes, which will (if accessed via the link) make them accessible publically, regardless of their original access restrictions
• can make the links expire, make the notes changeable or read-only etc

Pin

• Create pin-boards for certain topics - either by defining a topic or by using a tag as its base
• Items can be part of many pinboards at the same time (many-to-many relationship)
• Pinboards can be shared (similar to notes above) and this will supersede the access restrictions of the individual notes

Super-Public mode:

• Even if board is set to not show public items to non-registered visitors, notes could be set to super-public mode (needs better name) - and they would show up for non-registered
• essentially this creates 3 modes of notes: Always public, default access restrictions, always private - instead of the 2 currently default, always private