The other day, I got an advertisement encouraging me to revisit an account I once created at Freshbooks. It was a pretty attractive invite too, nice looking and offered good visual incentive to get back with their program. This ad, and its distribution, was obviously costly.
I logged into the derelict account and took a look around. Much had improved and it was motivating me to click that upgrade button. Eventually I just had to review pricing, I was damn near sold and needed very little to push me to go ahead.