Script to monitor the current activity on SQL server

The following script will output the current current processes running on SQL server:

SELECT
   [Session ID] = s.session_id,
   [User Process] = CONVERT(CHAR(1), s.is_user_process),
   [Login] = s.login_name, 
   [Database] = ISNULL(db_name(r.database_id), N''),
   [Task State] = ISNULL(t.task_state, N''),
   [Command] = ISNULL(r.command, N''),
   [Application] = ISNULL(s.program_name, N''),
   [Wait Time (ms)] = ISNULL(w.wait_duration_ms, 0),
   [Wait Type] = ISNULL(w.wait_type, N''),
   [Wait Resource] = ISNULL(w.resource_description, N''),
   [Blocked By] = ISNULL(CONVERT (varchar, w.blocking_session_id), ''),
   [Head Blocker] =
      CASE
         -- session has an active request, is blocked, but is blocking others
         WHEN r2.session_id IS NOT NULL AND r.blocking_session_id = 0 THEN '1'
         -- session is idle but has an open tran and is blocking others
         WHEN r.session_id IS NULL THEN '1'
         ELSE ''
      END,
   [Total CPU (ms)] = s.cpu_time,
   [Total Physical I/O (MB)] = (s.reads + s.writes) * 8 / 1024,
   [Memory Use (KB)] = s.memory_usage * 8192 / 1024,
   [Open Transactions] = ISNULL(r.open_transaction_count,0),
   [Login Time] = s.login_time,
   [Last Request Start Time] = s.last_request_start_time,
   [Host Name] = ISNULL(s.host_name, N''),
   [Net Address] = ISNULL(c.client_net_address, N''),
   [Execution Context ID] = ISNULL(t.exec_context_id, 0),
   [Request ID] = ISNULL(r.request_id, 0),
   [Workload Group] = N''
FROM sys.dm_exec_sessions s 
LEFT OUTER JOIN sys.dm_exec_connections c ON (s.session_id = c.session_id)
LEFT OUTER JOIN sys.dm_exec_requests r ON (s.session_id = r.session_id)
LEFT OUTER JOIN sys.dm_os_tasks t ON (r.session_id = t.session_id AND r.request_id = t.request_id)
LEFT OUTER JOIN
(
   -- In some cases (e.g. parallel queries, also waiting for a worker), one thread can be flagged as
   -- waiting for several different threads. This will cause that thread to show up in multiple rows
   -- in our grid, which we don't want. Use ROW_NUMBER to select the longest wait for each thread,
   -- and use it as representative of the other wait relationships this thread is involved in.
   SELECT *, 
      ROW_NUMBER() OVER (PARTITION BY waiting_task_address ORDER BY wait_duration_ms DESC) AS row_num
   FROM sys.dm_os_waiting_tasks
) w ON (t.task_address = w.waiting_task_address) AND w.row_num = 1
LEFT OUTER JOIN sys.dm_exec_requests r2 ON (r.session_id = r2.blocking_session_id)
ORDER BY s.session_id;