Via the Statement Monitor you can see what users, from which workstation, are issuing what statements. It shows the number of rows affected by the statement, statement "quantum" and the status of the statement.
The Statement Monitor has three different tabs, all showing the same information - but in a different arrangement. From a plain list of all statements to grouped per workstation or username, in order to make things more clear.
Statement Monitor - statements grouped per workstation
You can cancel running or inactive statements via the Cancel Statement button. This will send instructions to InterBase to cancel the statement.