I always like to take a look at what tools Etsy is featuring in their Handmade Code series on the Storque blog. Usually I either think it might be useful and add it to my Squidoo lens on Etsy Tools or bypass it if I don't see it as very useful. However they recently featured a tool I had to try out and I find it really interesting because I love stats.
Metricly lets you see data about your shop in pretty easy to understand graphs. Here's one on New vs Repeat Sales (I edited it to show from the 1st of this year and number of items sold, the default is the last 12 months and the $ amount of sales):
You can also connect other data sources such as google analytics for your Etsy shop. I need to play around with Metricly a bit more to figure out how that will work and if it gives any insight I can't get easily from my Analytics reports.