At Telepathy Labs, I worked on a large web-based administration tool for application customization. One feature of this tool is data management.
This was a challenging project, as I had to learn about SQL and schema diagrams in order to understand the desired functionality. Also, while I expected a more technical user for this tool, making sure that the design is as simple and user-friendly as possible was mentally simulating with the level of complexity in both the desired functionality and the scope of data expected.