three concentric circles of marketing ...
1. inner circle: traditional marketing, push, brochureware, web1.0 web-site etc.

2. middle-layer: engagement marketing, using blogs, discussion boards etc. on your web-site to engage your customers. Student 2 Student is an example. Channel 9 is an example.

3. outer-circle: "free" marketing, you are being discussed on discussion boards, on the blogosphere, content about you is being added to wikis etc. Use blog engines to find content, news readers to subscribe etc.

Just thought this was an interesting means of organizing marketing programs for web 2.0.