There are some really cool tools out there that will help you boost your sales. I'll start off with my top tips and will be adding more to this discussion whenever something pops up in my mind.
Here it goes:
FIVERR: Use the people on fiverr.com to promote your Etsy shop
Fiverr.com is a cool website on which people are willing to do almost about anything for exactly $5. These are very helpful if you need views, favorites and sales in your shop:
http://fiverr.com/debdebdeb/tell-14000-twitter-followers-in-the-artcraft-world-to-check-out-your-etsy-shop
This user will tell 14,000 Twitter followers in the art/craft world to check out your Etsy shop for $5
http://fiverr.com/dave1/tweet-your-etsy-item-to-28000-etsy-followers-and-guarantee-500-product-views
This user will tweet your Etsy item to his Etsy followers and guarantee 500 product views for $5
MAILING LIST: Use Aweber to automatically send out a coupon or message to your customers
www.aweber.com
I user Aweber to send out a 15% 'thank you' coupon code automatically (their system links to your Etsy account and pulls the information from it for you) when someone buys something in my shop. I also have some emails set up that will be send to them after a while, and their special Etsy templates make it easy to make the email look like your shop and drag and drop your etsy listings in there.
IFTTT: With IFTTT ('If this, then that') it is extremely easy to have your new Etsy products be published on other social media platforms.
www.ifttt.com
There are many, many ways to use IFTTT (ranging from 'email me the current weather report every morning' to 'whenever I add a listing, post a photo to my Facebookpage in this particular album'). You can even get a text message when you sell something. It's a great tool for automation and I honestly can't live without it.
HOOTSUITE: When you are managing more than one social media account, it can be quite time consuming to keep up with them. I use Hootsuite to get a clear overview of all my accounts on one screen. I can post new updates across all my social media platforms and reply to questions quickly.
www.hootsuite.com
Feel free to add some great tools when you know of any!