-- Start Date (US format - mm/dd/yyyy)
=DateAdd("d", -(WeekDay(Today(),2))+1, Today()) // yields: 8/1/2011

-- End Date (US format - mm/dd/yyyy)
=DateAdd("d", -1, DateAdd("d", 7-(WeekDay(Today(),2))+1, Today())) // yields: 8/7/2011

-------------------------------------------------------------------------

-- Start Date (european format - dd/mm/yyyy)
=Format(DateAdd("d", -(WeekDay(Today(),2))+1, Today()), "dd/MM/yyyy") //yields 01/08/2011

-- End Date (european format - dd/mm/yyyy)
=Format(DateAdd("d", -1, DateAdd("d", 7-(WeekDay(Today(),2))+1, Today())), "dd/MM/yyyy") // yields: 07/08/2011

1.  -- Start Date (US format - mm/dd/yyyy) 
2.  =DateAdd("d", -(WeekDay(Today(),2))+1, Today()) // yields: 8/1/2011 
3.   
4.  -- End Date (US format - mm/dd/yyyy) 
5.  =DateAdd("d", -1, DateAdd("d", 7-(WeekDay(Today(),2))+1, Today())) // yields: 8/7/2011 
6.   
7.  ------------------------------------------------------------------------- 
8.   
9.  -- Start Date (european format - dd/mm/yyyy) 
10.  =Format(DateAdd("d", -(WeekDay(Today(),2))+1, Today()), "dd/MM/yyyy") //yields 01/08/2011 
11.   
12.  -- End Date (european format - dd/mm/yyyy) 
13.  =Format(DateAdd("d", -1, DateAdd("d", 7-(WeekDay(Today(),2))+1, Today())), "dd/MM/yyyy") // yields: 07/08/2011 

-- Start Date (US format - mm/dd/yyyy)
=DateAdd("d",1-DatePart("d",Today()),Today()) // yields: 8/1/2011

-- End Date (US format - mm/dd/yyyy)
=DateAdd("d",-1, CDate(cstr(month(today.now())+1) + "/1/" + cstr(year(today.now()))) ) // yields: 8/31/2011

-------------------------------------------------------------------------

-- Start Date (european format - dd/mm/yyyy)
=CDate("01/" + cstr(month(today.now())) + "/" + cstr(year(today.now()))) //yields 1/8/2011

-- End Date (european format - dd/mm/yyyy)
=Format(DateAdd("d",-1, CDate(cstr(month(today.now())+1) + "/1/" + cstr(year(today.now()))) ), "dd/MM/yyyy") // yields: 31/08/2011

1.  -- Start Date (US format - mm/dd/yyyy) 
2.  =DateAdd("d",1-DatePart("d",Today()),Today()) // yields: 8/1/2011 
3.   
4.  -- End Date (US format - mm/dd/yyyy) 
5.  =DateAdd("d",-1, CDate(cstr(month(today.now())+1) + "/1/" + cstr(year(today.now()))) ) // yields: 8/31/2011 
6.   
7.  ------------------------------------------------------------------------- 
8.   
9.  -- Start Date (european format - dd/mm/yyyy) 
10.  =CDate("01/" + cstr(month(today.now())) + "/" + cstr(year(today.now()))) //yields 1/8/2011 
11.   
12.  -- End Date (european format - dd/mm/yyyy) 
13.  =Format(DateAdd("d",-1, CDate(cstr(month(today.now())+1) + "/1/" + cstr(year(today.now()))) ), "dd/MM/yyyy") // yields: 31/08/2011 

-- Start Date (US format - mm/dd/yyyy)
=DateSerial(YEAR(Today()),1,1) // yields: 1/1/2011

-- End Date (US format - mm/dd/yyyy)
=DateAdd("d", -1, DateSerial(YEAR(Today())+1,1,1)) // yields: 12/31/2011

-------------------------------------------------------------------------

-- Start Date (european format - dd/mm/yyyy)
=Format(DateSerial(YEAR(Today()),1,1), "dd/MM/yyyy") //yields: 01/01/2011

-- End Date (european format - dd/mm/yyyy)
=Format(DateAdd("d", -1, DateSerial(YEAR(Today())+1,1,1)), "dd/MM/yyyy") // yields: 
31/12/2011

1.  -- Start Date (US format - mm/dd/yyyy) 
2.  =DateSerial(YEAR(Today()),1,1) // yields: 1/1/2011 
3.   
4.  -- End Date (US format - mm/dd/yyyy) 
5.  =DateAdd("d", -1, DateSerial(YEAR(Today())+1,1,1)) // yields: 12/31/2011 
6.   
7.  ------------------------------------------------------------------------- 
8.   
9.  -- Start Date (european format - dd/mm/yyyy) 
10.  =Format(DateSerial(YEAR(Today()),1,1), "dd/MM/yyyy") //yields: 01/01/2011 
11.   
12.  -- End Date (european format - dd/mm/yyyy) 
13.  =Format(DateAdd("d", -1, DateSerial(YEAR(Today())+1,1,1)), "dd/MM/yyyy") // yields: 
14.  31/12/2011