I think it would be great to have a navigation bar on all Atlassian products that link to all other Atlassian products a company is using.

The reason for this is to assist with navigating between products for new users, and to give the products a single level of consistancy.

For this to work all products would require an administration screen where a standard header could be set which would contain the links from the current product to all the other products (that are configured)

Example:
If Company A is using Confluence, JIRA, Crowd, and Bamboo, they could easily access any of the other products in the suite from any other product in the suite. So if a user was in Confluence, they would be able to click on a single link in the header/tool bar/ navigation bar for Crowd, JIRA, or Bamboo and would get taken there straight away.