SELECT * FROM (select PARSING_USER_ID,EXECUTIONS,SORTS,

COMMAND_TYPE,DISK_READS,sql_text FROM v$sqlarea

order BY disk_reads DESC )where ROWNUM<10 ; 

SELECT se.sid,se.serial#,pr.SPID,se.username,se.status,

se.terminal,se.program,se.MODULE,se.sql_address,st.event,st.

p1text,si.physical_reads,

si.block_changes FROM v$session se,v$session_wait st,

v$sess_io si,v$process pr WHERE st.sid=se.sid AND st.

sid=si.sid AND se.PADDR=pr.ADDR AND se.sid>6 AND st.

wait_time=0 AND st.event NOT LIKE '%SQL%' ORDER BY physical_reads DESC

select a.username, a.sid,b.SQL_TEXT, b.SQL_FULLTEXT

  from v$session a, v$sqlarea b

where a.sql_address = b.address 

select b.SQL_TEXT,b.FIRST_LOAD_TIME,b.SQL_FULLTEXT

  from v$sqlarea b

where b.FIRST_LOAD_TIME between '2009-10-15/09:24:47' and

       '2009-10-15/09:24:47' order by b.FIRST_LOAD_TIME 

select OSUSER,PROGRAM,USERNAME,SCHEMANAME,B.Cpu_Time,STATUS,B.SQL_TEXT

from V$SESSION A LEFT JOIN V$SQL B ON A.SQL_ADDRESS=B.ADDRESS AND A.SQL_HASH_VALUE=B.HASH_VALUE order by b.cpu_time desc 

select address, sql_text, piece

  from v$session, v$sqltext

where address = sql_address

  -- and machine = < you machine name >

order by address, piece