There's an Etsy community on reddit, where you can post two "shameless plugs" about your own products a day. You can also ask questions and have discussions with other Etsy users. It's fun to see what products people are sharing and give "up votes" to the stuff you like.
I also learned about a site called Etsy on Sale which has tools to manage promotions for your Etsy shop--they give the option to put just one category of items in your shop on sale, rather than the shop-wide promotion you can do through Etsy itself. People can also see your items on the Etsy on Sale site, so it gives you a little more exposure.
I happened upon both of these links reading the "Business Topics" in the Etsy forums. Hopefully, more browsing and searching the forums will lead to other useful links.
Are there any links that have helped you with buying and selling on Etsy?