If you only have time to create one GMail filter, create this one. Find any email the HAS the word Unsubscribe and DOESN'T HAVE the words FW or RE and put it in a folder labeled "Optional"
Any email that has the option to unsubscribe from it probably isn't an essential email. These are the types of emails that may very well include some interesting information but do not require your time if you don't have it. If you want to be absolutely militant about your optional emails, check out the Technolicious version of this filter.
In case you don't know how to set up a GMail filter, see the screencast I created below.