https://help.salesforce.com/HTViewHelpDoc?id=custom_dates.htm&language=en_US

Relative Date Value Range
YESTERDAY Starts at 12:00:00 a.m. on the day before the current day and continues for 24 hours.
TODAY Starts at 12:00:00 a.m. on the current day and continues for 24 hours.
TOMORROW Starts at 12:00:00 a.m. on the day after the current day and continues for 24 hours.
LAST WEEK Starts at 12:00:00 a.m. on the first day of the week before the current week and continues for seven days.
THIS WEEK Starts at 12:00:00 a.m. on the first day of the current week and continues for seven days.
NEXT WEEK Starts at 12:00:00 a.m. on the first day of the week after the current week and continues for seven days.
LAST n WEEKS Starts at 12:00:00 a.m. on the first day of the week that started n weeks before the current week, and continues up to 11:59 p.m on the last day of the week before the current week.
NEXT n WEEKS Starts at 12:00:00 a.m. on the first day of the week after the current week and continues for n times seven days.
n WEEKS AGO Starts at 12:00:00 a.m. on the first day of the week that started n weeks before the start of the current week and continues for seven days.
LAST MONTH Starts at 12:00:00 a.m. on the first day of the month before the current month and continues for all the days of that month.
THIS MONTH Starts at 12:00:00 a.m. on the first day of the current month and continues for all the days of that month.
NEXT n MONTHS Starts at 12:00:00 a.m. on the first day of the month after the current month and continues until the end of the nth month.
LAST n MONTHS Starts at 12:00:00 a.m. on the first day of the month that started n months before the current month and continues up to 11:59 p.m on the last day of the month before the current month.
n MONTHS AGO Starts at 12:00:00 a.m. on the first day of the month that started n months before the start of the current month and continues for all the days of that month.
NEXT MONTH Starts at 12:00:00 a.m. on the first day of the month after the current month and continues for all the days of that month.
LAST 90 DAYS Starts at 12:00:00 a.m. 90 days before the current day and continues up to the current second. (The range includes today.)
NEXT 90 DAYS Starts at 12:00:00 a.m. on the day after the current day and continues for 90 days. (The range does not include today.)
LAST n DAYS Starts at 12:00:00 a.m. n days before the current day and continues up to the current second. (The range includes today.)
NEXT n DAYS Starts at 12:00:00 a.m. on the next day and continues for the next n days. (The range does not include today.)
n DAYS AGO Starts at 12:00:00 a.m. on the day n days before the current day and continues for 24 hours. (The range does not include today.)
LAST QUARTER Starts at 12:00:00 a.m. on the first day of the calendar quarter before the current calendar quarter and continues to the end of that quarter.
THIS QUARTER Starts at 12:00:00 a.m. on the first day of the current calendar quarter and continues to the end of the quarter.
NEXT QUARTER Starts at 12:00:00 a.m. on the first day of the calendar quarter after the current calendar quarter and continues to the end of that quarter.
LAST n QUARTERS Starts at 12:00:00 a.m. on the first day of the calendar quarter n quarters ago and continues to the end of the calendar quarter before the current quarter. (The range does not include the current quarter.)
NEXT n QUARTERS Starts at 12:00:00 a.m. on the first day of the calendar quarter after the current quarter and continues to the end of the calendar quarter n quarters in the future. (The range does not include the current quarter.)
n QUARTERS AGO Starts at 12:00:00 a.m. on the first day of the calendar quarter n quarters before the current calendar quarter and continues to the end of that quarter.
LAST YEAR Starts at 12:00:00 a.m. on January 1 of the year before the current year and continues through the end of December 31 of that year.
THIS YEAR Starts at 12:00:00 a.m. on January 1 of the current year and continues through the end of December 31 of the current year.
NEXT YEAR Starts at 12:00:00 a.m. on January 1 of the year after the current year and continues through the end of December 31 of that year.
n YEARS AGO Starts at 12:00:00 a.m. on January 1 of the calendar year n years before the current calendar year and continues through the end of December 31 of that year.
LAST n YEARS Starts at 12:00:00 am on January 1, n+1 years ago. The range ends on December 31 of the year before the current year.
NEXT n YEARS Starts at 12:00:00 a.m. on January 1 of the year after the current year and continues through the end of December 31 of the nth year.
LAST FISCAL QUARTER Starts at 12:00:00 a.m. on the first day of the fiscal quarter before the current fiscal quarter and continues through the last day of that fiscal quarter. The fiscal quarter is defined in Setup at Company Profile | Fiscal Year.

Note
None of the FISCAL literal date values are supported when creating mobile custom views.
THIS FISCAL QUARTER Starts at 12:00:00 a.m. on the first day of the current fiscal quarter and continues through the end of the last day of the current fiscal quarter. The fiscal quarter is defined in Setup at Company Profile | Fiscal Year.
NEXT FISCAL QUARTER Starts at 12:00:00 a.m. on the first day of the fiscal quarter after the current fiscal quarter and continues through the last day of that fiscal quarter. (The range does not include the current quarter.) The fiscal quarter is defined in Setup at Company Profile | Fiscal Year.
LAST n FISCAL QUARTERS Starts at 12:00:00 a.m. on the first day of the fiscal quarter n fiscal quarters ago and continues through the end of the last day of the previous fiscal quarter. (The range does not include the current fiscal quarter.) The fiscal quarter is defined in Setup at Company Profile | Fiscal Year.
NEXT n FISCAL QUARTERS Starts at 12:00:00 a.m. on the first day of the fiscal quarter after the current fiscal quarter and continues through the end of the last day of the nth fiscal quarter. (The range does not include the current fiscal quarter.) The fiscal quarter is defined in Setup at Company Profile | Fiscal Year.
n FISCAL QUARTERS AGO Starts at 12:00:00 a.m. on the first day of the fiscal quarter n fiscal quarters before the current fiscal quarter and continues through the end of the last day of that fiscal quarter.
LAST FISCAL YEAR Starts at 12:00:00 a.m. on the first day of the fiscal year before the current fiscal year and continues through the end of the last day of that fiscal year. The fiscal year is defined in Setup at Company Profile | Fiscal Year.
THIS FISCAL YEAR Starts at 12:00:00 a.m. on the first day of the current fiscal year and continues through the end of the last day of the fiscal year. The fiscal year is defined in Setup at Company Profile | Fiscal Year.
NEXT FISCAL YEAR Starts at 12:00:00 a.m. on the first day of the fiscal year after the current fiscal year and continues through the end of the last day of that fiscal year. The fiscal year is defined in Setup at Company Profile | Fiscal Year.
LAST n FISCAL YEARS Starts at 12:00:00 a.m. on the first day of the fiscal year n fiscal years ago and continues through the end of the last day of the fiscal year before the current fiscal year. (The range does not include the current fiscal year.) The fiscal year is defined in Setup at Company Profile | Fiscal Year.
NEXT n FISCAL YEARS Starts at 12:00:00 a.m. on the first day of the fiscal year after the current fiscal year and continues through the end of the last day of the nth fiscal year. (The range does not include the current fiscal year.) The fiscal year is defined in Setup at Company Profile | Fiscal Year.
n FISCAL YEARS AGO Starts at 12:00:00 a.m. on the first day of the fiscal year n fiscal