Filtering opportunities based on expiration date

Hello,

I am trying to create a view which will store all opportunities which have estimated close date past due. 

If my logic is correct then I will have to do following:

1) Add a status option as Expired under status Open

2) have a field which can store current date (I don't know whether I can have such a field)

3) create a business logic which can subtract Estimated close date from Current date and if the difference is 1 or more then set the status reason as 'Expired'

4) then create a view which will contain opportunities with status reason as expired.

my problem is that there is no such field which can give me current date value.  Any suggestion if there is another way of doing this or how to accomplish the result using my approach? will calculated field will give current date option?

Thanks in advance.