I know this sounds like a point-whoring question but let me explain where I'm coming from.
Out of college I got a job at a PHP shop. I worked there for a year and a half and thought that I had learned all there was to learn about programming.
Then I got a job as a one-man internal development shop at a sizable corporation where all the work was in C#. In my commitment to the position I started reading a ton of blogs and books and quickly realized how wrong I was to think I knew everything. I learned about unit testing, dependency injection and decorator patterns, the design principle of loose coupling, the composition over inheritance debate, and so on and on and on – I am still very much absorbing it all. Needless to say my programming style has changed entirely in the last year.
Now I find myself picking up a php project doing some coding for a friend's start-up and I feel completely constrained as opposed to programming in C#. It really bothers me that all variables at a class scope have to be referred to by appending '$this->' . It annoys me that none of the IDEs that I've tried have very good intellisense and that my SimpleTest unit tests methods have to start with the word 'test'. It drives me crazy that dynamic typing keeps me from specifying implicitly which parameter type a method expects, and that you have to write a switch statement to do method overloads. I can't stand that you can't have nested namespaces and have to use the :: operator to call the base class's constructor.
Now I have no intention of starting a PHP vs C# debate, rather what I mean to say is that I'm sure there are some PHP features that I either don't know about or know about yet fail to use properly. I am set in my C# universe and having trouble seeing outside the glass bowl.
So I'm asking, what are your favorite features of PHP? What are things you can do in it that you can't or are more difficult in the .Net languages?