The hunt for software

In this case I am Ignorant, so I turn to the teeming Millions:
Does anybody know of a good software to use as
a tool for follow ups to client visits?
I have searched the net over and cant find anything that
will allow me to catalog my clients info along with a
a page for notes that will alert me when I need to contact
them again, sort of like a debt collection program but
without the $$$ part involved.