I've designed and instigated what I hope is a Web 2.0 task. It is a little ambitious and would need to start bit by bit, but it might just work! I've posted it within my blog here. Thanks.
A simpler alternative would be to take a discussion topic like 'Are families in fashion?' and have groups of students find out information, learn from each other and the web, and prepare for an interactive outcome such as a formal debate, a letter to..., a leaflet, a presentation, a wiki, etc. These projects could be exchange projects or simply class projects. A few ideas are here.