Keep in mind, I'm terrible at coming up with business ideas and even worse at marketing. Yet, somehow, I still have the nagging desire to do a startup.
MarketingBar Similar to http://www.hellobar.com create a service where you can install a bar on the to of your site (javascript) and allow targeting the bar with 3 types of messaging (link, question, offer).
1. Simple Link - e.g. Follow us on Twitter @username 2. Ask a question with Call to action, e.g. We love talking to people on social media: What's your @username? [input box] or even a Yes/No e.g. Are you in the market for some new pants (yes [radiobutton] / no [radio button] 3. Offer call to action - Take 10% off your order today with coupon code: 10off
Allow for a CMS like system for targeting each message based on URL and/or referal (.e.g if the refereal is twitter, show message about following or capturing their twitter username).
Bonus - integrate https://github.com/codejoust/session.js so now you can track each visitor and their entire path showing what message was shown and what pages they visited.
For ideas take a look at http://www.getbackstory.com https://mixpanel.com/activity-feed/ and http://www.springmetrics.com/
Hope that helps or gets the ball rolling on some ideas :) Feel free to hit me up if you want to talk more.