Calculate Case or Task Age in Business Hours

This requirement which popped up a few weeks back - a field which can give the case age in business hours [excluding saturdays and sundays]. There was no function in salesforce which provided me the day given the date. I came about with a round about logical solution - a formula(number with 0 digits after decimal point) field which excludes saturdays and sundays when calculating the case age.

CASE(
MOD(DATEVALUE(CreatedDate) - DATE(1900, 1, 7), 7),
0, (TODAY() - DATEVALUE(CreatedDate)) - 1 - FLOOR((TODAY() - DATEVALUE(CreatedDate))/7)*2,
1, (TODAY() - DATEVALUE(CreatedDate)) - FLOOR((TODAY() - DATEVALUE(CreatedDate))/7)*2,
2, (TODAY() - DATEVALUE(CreatedDate)) - FLOOR((TODAY() - DATEVALUE(CreatedDate))/7)*2,
3, (TODAY() - DATEVALUE(CreatedDate)) - FLOOR((TODAY() - DATEVALUE(CreatedDate))/7)*2,
4, (TODAY() - DATEVALUE(CreatedDate)) - FLOOR((TODAY() - DATEVALUE(CreatedDate))/7)*2,
5, (TODAY() - DATEVALUE(CreatedDate)) - 2 - FLOOR((TODAY() - DATEVALUE(CreatedDate))/7)*2,
6, (TODAY() - DATEVALUE(CreatedDate)) - 2 - FLOOR((TODAY() - DATEVALUE(CreatedDate))/7)*2,
null)

Exclude Saturdays and Sundays while calculating the Due Date

Requirement: Calculate Due Date from Start Date and Number Of Business Days
Due Date = Start Date + Number of Days [excluding Saturdays and Sundays]
An apex trigger to calculate the Due date on an insert or update is rather time consuming than just creating a formula field with some logic.

The below formula field calculates the Due Date [which is the new formula] provided the Start Date [StartDate__c] and Number Of Days to be added to the Start Date [NumberOfDays__c] excluding Saturdays and Sundays.

CASE(
MOD(StartDate__c - DATE(1900, 1, 7), 7),
0, (StartDate__c) + NumberOfDays__c + FLOOR((NumberOfDays__c-1)/5)*2,
1, (StartDate__c) + NumberOfDays__c + FLOOR((NumberOfDays__c)/5)*2,
2, (StartDate__c) + NumberOfDays__c + FLOOR((NumberOfDays__c+1)/5)*2,
3, (StartDate__c) + NumberOfDays__c + FLOOR((NumberOfDays__c+2)/5)*2,
4, (StartDate__c) + NumberOfDays__c + FLOOR((NumberOfDays__c+3)/5)*2,
5, (StartDate__c) + NumberOfDays__c + CEILING((NumberOfDays__c)/5)*2,
6, (StartDate__c) - IF(NumberOfDays__c>0,1,0) + NumberOfDays__c + CEILING((NumberOfDays__c)/5)*2,
null)