That reminds me of a Rosetta code problem I did a few years ago at Perl Monks.
Write a Perl function to reverse a string of words. For example, given an input string of:the function should produce:
When you've written your function, you can view many solutions to this problem in Perl and other languages at Five Ways to Reverse a String of Words (C#, Perl 5, Perl 6, Ruby, Haskell).
Update: Two more.
Given an input string, for example "ZBBBCZZ", produce a list, for example, ["Z", "BBB", "C", "ZZ"]. That is, break the input string into pieces based on change of character. Solutions at Yet Another Rosetta Code Problem (Perl, Ruby, Python, Haskell, ...).
Given a list of strings, for example ("a", "bb", "c", "d", "e", "f", "g", "h"), and a chunksize, for example 3, write a subroutine to return a multi-line string, for example:
The output string must contain a single space between each array element and a newline every chunksize items. Note that no trailing space is permitted on any line and the last line must be properly newline-terminated. Solutions at Rosetta code: Split an array into chunks.