Here are some examples of UI patterns:
Input Controls
Stacked Tabs
Inline Input Adder
One Page Wizards
Overlay
Generally each section will explain the pattern, how and why to use, and gives a handful of graphics as real world examples.
As an additional resource, you can also visit ThemeForest’s admin template site and browse through their many products and get pictures and live tours of very well designed and styled admin pages. I personally have used a few of these templates for data heavy sites.
Hope these help you out some.
7/25/18 Update: While it is hard to keep links from nine years ago working, it seem that the website which hosted the UI examples is now gone. Read Farewell from Patternry for further information.