I found out about craftweasel when browsing the Etsy forums and thought it was worth sharing.
One part of the site offers a 'shop stats tool', where you simply enter your Etsy shop name and it supplies you with loads of valuable data, such as a graph of your tags with most views/day (pale pink), a graph of your tags with the highest price (necklace) and a graph of your most-used tags (bangle)
The other part of the site is the 'tag finder tool' which -
"helps you choose the best set of tags for your Esty items. Tag finder will generate graphs showing the price and views per day of items with your query, as well as on related tags. This lets you see which tags will be likely to bring the highest number of views to your Etsy items."
It lets you see a distribution of prices, graph of related tags with most views/day and related tags.
I put in Pearl Cluster Bracelet and had a chuckle to find that AMIDesigns is rated one of the related tags to use :)