Twitterfeed is a great site that allows you to set up rss feeds of your zazzle shops, and blogs to automate tweets.
What it does is checks your rss feed every specified time period (30 minutes, one hour, once per day) and then it tweets if it finds anything new a set number of tweets.
I usually set it to every 30 minutes and allow it to tweet 1-2 lines. this will only tweet if i post something new, and it will not post everything since it is limited to how many it can tweet. It will also feed to facebook however i have found a better app on facebook for this.
You can choose to sign in with an email address or openid – it does not matter as long as you always use the same way every time.
You will then create a new feed – you will need a new feed for each shop you have and each blog you have.
the feed url for your shop can be written 2 different ways: (replace SHOPID with your shopid)
http://feed.zazzle.com/SHOPID/feed?ft=gb&at=238666735725955039 where you replace the # at the end with your refferal code. I have found this seems to error more often then the basic feed
http://feed.zazzle.com/SHOPID/rss this one you do not get any referral
once you enter this you will click advanced and you can add #tags that will appear on ever tweet from this feed. i recommend using #zazzle and #SHOPID with your shop id.you could also add #custom or #printed. On this area you also will set how many and how often you want twitter feed to check for new items and post to your twitter.
If you intend to feed to facebook i recommend you uncheck where it says feed image also, as it will NOT pick up the correct image.
You will then proceed to step 2 at the bottom and choose twitter and link it to your twitter account so it will tweet there.