When you say ecommerce, do you specifically want customers to buy through your website without talking to salespeople?
For training and event registration, Webex and Gotomeeting have solid integrations. Others may be able to provide pros/cons of each.
For online sales transactions, there aren't many products specifically promising integration. One company promising integration soon is Episerver:
Hope that helps
Curious to know if anyone else has had any experience with this? Anyone use Episerver?