This is a useful trick if you use Twitter. TwitterFeed will take the RSS feed from your shop and when you list new items it will send tweets through your account announcing them. Here's how it works:
1: Set up an account on TwitterFeed
2: Click Create New Feed
3: Input your Twitter username and password
4: Input the URL for your RSS Feed
5: Select update frequency. Every hour is usually good.
6: Select the maximum number of tweets it will send at once. This is important, send too many automatic tweets about your items and your followers will get annoyed. I use 3 and I wouldn't go over 5 especially if you add new items very frequently.
7: Include title and decription. Probably a good idea to leave this alone but if you want you could have only titles displayed.
8: Prefix each tweet with: Write something short and simple to go at the beginning such as "New from my shop:"
9: Click Create to start sending your feed to twitter. You should see the tweets show up the next time you list an item for sale.
If you have multiple shops or want to include your blog as well just repeat steps 2-9 again. I would suggest that the more feeds you have the fewer max tweets you set for each feed since if you have 2 feeds set to 5 and update both with 5 or more items in an hour Twitterfeed is going to send 10 tweets to your timeline.