Keeping track of what has been done with my sites?

Now that my portfolio of sites have grown since I first started, I am having some trouble remembering what Ive done to the different sites and trouble keeping track of stuff that has to be done.

How do you guys that have a bunch of sites keep track of stuff that has been done and needs to be done? Any good programs, excel templates or other things you can share?

 

I am trying to figure this out myself, for sites as well as all my affiliate programs.