查找具有特定属性的所有类

I've got a .NET library in which I need to find all the classes which have a custom attribute I've defined on them, and I want to be able to find them on-the-fly when an application is using my library (ie - I don't want a config file somewhere which I state the assembly to look in and/ or the class names).I've got a .NET library in which I need to find