As well as being able to chat you can exchange documents easily. Simply browse to attach a document and it'll show up to the person they are chatting with. They can accept or decline it there and then.
You can also search the 'Chat' Archive - either by keyword or by just perusing your list of 'Chats'. The full transcript of each 'Chat' is available to view, inclusive of date and time stamps.
It's simple, easy & useful!