http://byecycle.sourceforge.net/ looks like a cool idea. The homepage has a wink demo of the plugin (very nice). Byecycle will display a dependency graph of you modules and highlight dependency cycles (plugin for Eclipse). This makes it easy to see problems in design. One realy cool features of byecycle is the way performs automatic layout. The layout engine will keep shifting the diagram as it finds better layouts. Also, check out the people behind this plugin. Some really smart folks.
Yes, a code metrics tool could provide similar information. But the cool graph display makes this a lot more fun. Plus the layout helps you understand the dependencies. Hopefully, if you system is well designed the layout would show your architecture layers since it tries to make the arrows go top to bottom.