SharePoint doesn't provide an easy way to share data  across Site Collections (which you must have, since you have multiple Web Applications.) If the content  is in the same Site Collection, you can use the Content Query Web Part to pull information from certain locations in the Site Collection. However, if your content lives in three different Web Applications, there's no good out of the box way of sharing  that content. You would need to write custom code, using the API or the SharePoint Web Service, to consume the content in different Site Collections.