My plugin allowed you to put in your hotel when you traveled. Then it showed a list of your current & past customers' offices that were within X miles. Now you can fire off those "btw, I'll be in town in 2 weeks, we should talk about X" emails well in advance.
If I had to do it now, I'd tie into Tripit or Google Calendar to get the most accurate info, pull the data from your CRM, and send you an email with some "last contact" info & links to email them.
Oh.. and I'd make it a monthly charge instead of a one-time purchase.
I think the more important aspect is that the benefits happen regularly. If you close an extra deal a year or lower churn a tiny bit, it's a huge ROI. Which says to me that the price should be non-trivial..
It's since turned there is a demand for this beyond our one client too thankfully.
I think it's helped that this product is aimed at businesses primarily too. With a higher price point we won't need a mass volume of clients to be profitable reducing demand on customer service requests etc.
For example, do research that shows that 7% of companies in industry XYZ use certain CRM. Analyze that industry and see what common use cases and pain points are. Somehow figure out what the CRM is missing for that industry. Validate the idea before building it by reaching out to said companies.
There would be a lot more to it, but basically a plugin for established software a company already uses is much easier and less risk to sell when you are a small shop.