There is a lot of tacit knowledge about companies and its operations, which is never  formally documented. One way to encourage sharing is to create mind maps on certain topics collaboratively. One example of similar approach in public social media is this mind map started by Andrew Wilcox on different mind-mapping software solutions.

Studies claim that it is easier for people to process information presented in mind maps and they also help distilling only the most important. 

Similar approach can be used in generating new ideas, seeking feedback, etc. One person just needs to start a mind map and invite other colleagues to join.