I'm a bit like you, I've coded PHP for over 8 years. I had to take a .NET/C# course about a year ago and I really enjoyed the C# language (hated ASP.NET) but it made me a better PHP developer.
PHP as a language is pretty poor, but, I'm extremely quick with it and the LAMP stack is awesome. The end product far outweighs the sum of the parts.
That said, in answer to your question:
http://uk.php.net/SPL
I love the SPL, the collection class in C# was something that I liked as soon as I started with it. Now I can have my cake and eat it.
Andrew
