Hey friend you can post all your projecct related problems in my thread..
for solution to your problem , i will suggest start on some content management systems like dotnetnuke portals.. then you can incorporate differnt formats and support for dffernt datas and view features for them ... also impleemnt categorization of data based on format .. and context.
Dificult feature is implementing support for differnt formats .. use XML for that as much as you can..
I hope that answers your query .. mark this as answer and ask more questions in my thread..