Take a look at Limbic~Region's excellent Tutorial entitled Getting Matching Items From An Array, in which he discusses several solutions including the grep method described above and one that uses List::Util's first function.

Also, don't forget about Super Search and the Categorized Questions and Answers section, which has a large collection of posts in the QandASection: arrays category, including How do I find the position of an element in an array? and How can I find the index of the biggest element in an array?.