Exposing a single field to users to create new nodes from a page
So you want to create something like simplistic Twitter/Facebook wall? Check following modules:
Microblog

Users can publish microblog updates, follow and be followed by other users, and reply to other users' microblog updates.
Module also provides &quot;public timeline&quot; page as well as followers and following pages, and a block of &quot;recent microblog updates.&quot;

Drupal 6 &amp; 7: https://drupal.org/project/microblog
Statuses (Social Microblog)


Provides status updates / microblogs like Facebook's Wall / News Feed, Twitter's Timeline, and Yammer's Feed. Users can update their own status or write messages to other users, nodes, Organic Groups, taxonomy terms, or other entity types. @mentions and #hashtags are supported, as well as comments on status updates, viewing conversations between users, the ability to &quot;like&quot;/&quot;reply&quot; to/RT a message, automatic updates without page refreshing, and integration with over 20 modules.

For Drupal 6: https://drupal.org/project/facebook_status
For Drupal 7: https://drupal.org/project/statuses