Summary: Interesting data service with innovative visualizations and some truly useful info. Limited number of categories minimizes its usefulness. Cost: $15/month, or $10/month with coupon code INDYAUTHOR (if it’s still active). Kindle Trends is a fairly new service that sends weekly newsletters to your email with in-depth data about a number of genres. If it covered all the genres, it would be an immediate recommend, as you get a lot of data for the price, though as with most things data-oriented, it takes a fair amount of knowledge and work to massage that data into actionable plans. However, currently it…