Larman has given a very good practical example for Using the Composite pattern in his example of building NextGen POS System.
He used the Composite pattern for applying single/composite of pricing stratagies for giving reduction in price of the goods we buy from a store like WALMART. Some how I feel the Larman's application of patterns using one practical example convinient and easy to remember than using Design Patterns by Gamma, which is a Dictionary of Patterns with out having the proper strategy for looking for patterns (of course with experience one can, but then no need of reading of a book)
You can look for about Composite Patterns in Page 358 of Larman's book on Applying UML and Patterns.
Hope this helps.