Little Things -- GMail (1 of ?)
Its the little touches that makes certain products stand out. If you click on the ‘trash’ folder and its empty you see:
No conversations in the trash. Who needs to delete when you have 1000 MB of storage?!
The first time you see it is amusing (or i need a life). When you think about it the message itself is actually positive reinforcement for the service. It implies careful thought has been given to the storage requirements. I like it.