“Wikipedia is the best thing ever. Anyone in the world, can write anything they want about any subject. So you know you are getting the best possible information.” - Michael Scott from The Office.
Wikipedia is a great resource for learning and is unbelievably reliable despite its flaws. I think that the marketing entries are pretty weak and the marketing community can make it a lot better. There are now wikibooks, which are open-source textbooks. There is even a marketing wikibook which is just a few pages. If you've never been a part of mass collaboration, this is a tremendous opportunity to share your wisdom and contribute. Imagine the accomplishment of being one of the primary authors of the marketing wikipedia textbook that is read all over the world (unless someone edits it).