I don't think the space is too crowded. For many opportunities, the sales force necessary and the dollar opportunities make it a significant challenge.
Groupon and LivingSocial have to maintain a huge sales force to keep new daily deals in the pipeline. SMB's aren't serving themselves.
Square is a one-time purchase with recurring revenue for the business, and a massive benefit to the business. Square also has a significant amount of money to spend on marketing.
Google is the go to solution for e-mail, so again, a no brainer.
Innovation (technical) isn't the solution to everything. I believe to break into this space you need sales innovation as well. Remember, many people in this space are non-technical, so selling them a technical solution that they don't NEED can be a challenge.