On the Blue Parabola blog Matthew Turland has written up a post about a PHP something that might need a bit more love - the Standard PHP Library.

If any PHP extension is underrated, it's probably the SPL (Standard PHP Library). From what I can tell without having been involved in its development, its purpose is somewhat similar to the STL. A while back, it was useful mainly for allowing class instances to be iterable and simulate array access. [...] Using the SPL classes actually turned out to be pretty straightforward once you got your hands on a good starting guide or two to help you beat the learning curve.

He mentions a few of the things offered by the SPL like the SplFixedArray/SplFastArray, Iterators, SplDoublyLinkedList, SplStack and SplQueue (among others). He also includes some benchmarks running standard code (like normal arrays) against a SPL counterpart - the SPL side beat the normal side hands down. Check out the full post for all of the numbers and comparison types.