An older version of this code is also available here: http://www.squeaksource.com/HttpSsp.html
This code lets you create a web application using Smalltalk Server Pages with Smalltalk code embedded in webpages. The Smalltalk code gets executed when the page is rendered which allows you to fill in parts of the page dynamically using Smalltalk code. This is very similar to ASP or JSP but with Smalltalk.
I have used this framework personally to build a couple sites and it makes for very clean code.
The framework is very minimal. It aims to help but still stay skinny.