We are officially using Google sites for some simple client sites. It allows the wiki access, super easy to setup, you can use Google Forms 01 | 02, use Google Moderator to Crowdsource Group Questions.
The next question is, how to implement ecommerce (adding an ecom componenent - like a module for adding a cart/checkout/etc.).
Most carts are really lacking. This is whats hot now: Magento - an open source cart, php5, object oriented, skins, etc. For custom apps, we're using zend framework and symfony framework.
Here are some easy examples: SummitChase, AlcovySurveying.
This post was completed in part by William Gorman at ContigoTech.com.