Well, better late than never: From now on I am going to think twice when I need a piece of functionality on the client.
Do read this article by Douglas Crockford:
BTW: What do you think of multiple inheritance. We used to be able to use it in the C++ days (C++ is still around but anyway). Do you miss it in C# or Java? (I mean multiple inheritance of classes not interfaces i.e. class c inherits class a and class b. In C# and Java you can inherit form max one class and implement as many interfaces as required. But of course interfaces do not include base implementations…).
Also: Can you give me your best example where you really missed multiple inheritance?