There are whole categories of new startups that cater to e-commerce sites:

* new analytics tools that understand the need to segment customers and track LTV

* abandoned cart recovery

* automating lifecycle e-mails

* making e-mail marketing easier for non-technical store owners

* connecting stores to all the comparison shopping / product ad sites with their separate feed formats (Google Shopping / Amazon Product Ads / Shopzilla / etc)

* rehosting stores to multiple platforms (e.g. take your Shopify store and sell on Facebook)

* automating fulfillment or quoting and purchasing individual shipping labels for small sellers

* improving customer service

If you're interested in who's servicing e-commerce companies, just look at the app stores of the new generation of e-commerce hosts like Shopify: http://apps.shopify.com/