Here are a few project ideas based on managing complex data:
Create an image viewer to preview and sort an archive of digital photographs. The only manual part would be getting a list of filenames (which you could do with an application server such as ColdFusion). It would be cool to give users a way to associate keywords with any individual photo. Then, they could create lists (well, arrays) of photos that match a particular query. Naturally, users will want to save any settings between sessionsso you need to apply skills covered in the next chapter regarding the local shared object. Macromedia actually produced a sample app like this called My Photo included in the Developer Resource Kit Volume 2, but I'd like to see something that enables users to add the keywords and do searches.
Alright, so you probably won't make your first million doing this game, but it's a good exercise. You can store the state of the game board in a nested array. Make a mode to play against the computer for an added challenge. Another good game to try is Concentration. You'll want to find an array-shuffling routine to randomize the board.
Take any data source to which you have access, think about how best to visually represent the data, and create a graph. You may want to check out the various drawing methods (listed as "Drawing Methods" under the Movie Clip object references). It really depends on how you want to create the graph. You can actually do quite a lot by placing clips onstage (like we did with the library and Olympic medal examples earlier). Ideally, you should make your code as adaptable as possible. For example, a nice challenge is to make it calculate a scale factor based on the range (from low and high) of values you happen to collect. Check out the Flash Charting components (available at http://www.macromedia.com/exchange) for a great model. (Naturally, you should strive to find better/different ways of making graphs.)