Looking for an online, out of the box solution for sharing and managing content

Hi All,

Perhaps you would have some suggestions - I'm looking for an online, out of
the box solution for sharing and managing content.

Primary goals the solution has to meet:

1. Manage and classify content items
2. Share content items with other people
3. Move content items' data between different systems

*Content item* is a piece of text, usually less than 1000 characters long.

Manageable

- classify content items based on updatable categories
- manage categories, including the ones assigned to existing content
items

Shareable

- quick and easy access for everyone, users and administrators
- form discussions on particular content items (add comments)

*
*Portable

- import a large number of content items at once (100-1000)
- export content items and any comments left on them (additional import
data TBD, e.g. date, email, username, list of categories categories)
- use excel or CSV format to import/export data

I considered using a blog platform for this, but blogs I've looked at had
issues with managing categories and transfering data in and out. Perhaps you
may know of a blog that meets these criteria?

I appreciate any input you can have.

Best,
Konrad