I've been using Marmalead for a couple months now and I have learned so much! I'm really loving the latest update to Marmalead that analyzes my Etsy listings and shows me which ones need the most work and goes into detail about how to improve it. The tag keyword clouds have given me some great keyword suggestions as well. The marmameters are very easy to understand and I've been using Marmalead to try to come up with new products to sell on Etsy. It's a wonderful research tool.
Also, I'm a HUGE fan of the podcast, I look forward to each episode and the longer the better. I listen while I make the things I sell on Etsy.