OSM is a tool to capture all SQL statements and archive to file in real time and monitor how connected sessions use database instance resources in real time. You can obtain an overview of session activity sorted by a statistic of your choosing. For any given session, you can then drill down for more detail. You can further customize the information you display by specifying manual or automatic data refresh, the rate of automatic refresh.
In addition to these useful monitoring capabilities, OSM allows you to send LAN pop-up message to users of Oracle sessions.