If you go to the calender, check 'work week' as display, then you can see 
that left of monday and earlier than the earliest hour displayed, there is 
a grey field which is about 1/2 inch in square.
I would find it extremly usefull if this field would be used to display the 
current calender week number in a big font, 14pt or so would fit in there I 
think.
I could send you a screenshot if you like, tells it more exactly than 
houndreds of lines of text can :-)
Feature is missing in outlynch as well, and that's very sad for industry 
jerks who always think in calender weeks (like me and my colleagues)