Usage of shortcuts while entering dates
Entering a date is a click/keyboard and brain intensive exercise. If today is Thursday 26-05-2011, and you want to enter next Thursday as a date, you need to either think quite hard what date that could be (26+7=33, current month is May has 31 days, 33-31=2, next month is June, hence date is 02-06-2011) or you need to open a calendar, click on the corresponding cell, etc.
The whole process would be much easier on users if users could leverage shortcuts whereby:
t represents today's date
t+X represents today's date + X days
t-X represents today's date - X days
With this approach, if today users type t+7, the date should automatically expand to 02-06-2011.