Just posted a blog entry on the ArcGIS Server Blog. Check it out.
Blog talks about how to use Dojo Dijits – BorderContainer (dijit.layout.BorderContainer) and ContentPane (dijit.layout.ContentPane) to design your layouts for application. I have created a bunch of sample layouts with most of the commonly used layouts, check out the links below.
You an try the live sample at: http://serverapps.esri.com/templates/index.html
You can download the samples at: Resource Center Code Gallery