My GMail has a load of rules for auto-sorting emails. I have folders/tags for Orders, Newsletters and similar things. I also have folders for specific items such as emails from my credit card company, ISP, O2 and the like.
I used to hate a massive list of emails to go through every day on my GMail, so now I can go through stuff that is important much faster. With things like newsletters and notifcations I mass-nuke them every week or so.
My Outlook email is all sent to the Inbox, and I sort it into folders afterwards. I deal with a number of clients and I have several contacts with each client. It is nice to simply click on Client A folder and see everything relating to them without the need for searching.