Met with the first ad agency to show them the beta version of the product and get their thoughts on it. They agreed to use it for their own email signatures and said they would be interested in using it for distributing future email signatures to clients.
It was great to get some initial positive feedback, but I also realize that they know me and like me already, so there may be some of the "Mom Test" factor going on here where they don't want to give bad feedback. Paying customers will be much more valuable.
It's hard to show it off at this point, because all I see are the million things that are unfinished about it, but I know that I need to get some actual designers and agencies using the application to make sure it actually works and it solves the problem I am claiming that it solves.
So here goes...