On the ProDevTips blog, Henrik has written up an extensive tutorial with plenty of code examples on working with something inspired by a few other languages - fluent arrays and strings.

I've been working some with jQuery and Ruby lately, as you might know they both have very neat fluent interfaces for writing short and easily understandable code. Especially Ruby's array and string handling should be something that can be done in PHP so I started googling. [...] It's probably very possible that what I'm looking for is already part of some PHP framework or such but I didn't want to spend more time looking than being productive.

Based on some Ruby examples, he defines a set of functions that can be use to create these fluent interfaces to the common PHP variable types (contained in a class for easy use). The entire source can be downloded here.