I saw my teammate months ago using a hashtable in creating a lookup type of business objects. Since we have just started using .NET 2.0, i told him about the new feature that comes with it that can be useful in his current task, generics. I told him about the typesafe List of T and Dictionary of T which are the ones frequently used.
I was surprised later that when i was reading his code that generics was all over the place, it's kind of messy to read. Methods were passing around List<BusinessObject> here and there, etc. Not to mention the pain when you decided later that a collection/list of business objects should really be a dictionary type and you have to change the signatures of the involved methods.
Having said that, I prefer to introduce another class for the list type of business objects eventhough i don't have any added implementations List<T>. Just like the .NET 1.x way where i have the CollectionBase inheritors. That way, it would be easy for me if ever i needed to provide additional methods for it, , change it from a list type to a dictionary type, or even to read code (the last one is obviously relative).