I use my square a fair bit but I am pretty sure that the tape measure is my most used. Measure along and across all sorts of things. You can use it to find if something is square with it as well. In fact timber not being such a precise medium (god I use big words) the tape can sometimes be the best thing to use to find square.
I should use my roller stands as well more than I do. I have made plenty of mistakes running something through a machine which was really just a bit too long to do without the stands.
Studley