I used to have three--school, personal, and junk mail--but I consolidated a couple months ago and have only one. I haven't regretted that decision at all. Those extra ones were really unnecessary.
5, 1 personal and 4 work and business related.
I also have 3 mailing addresses. one for packages and stability never changes, personal 1 CA and 1 AZ, spend a lot of time both places.
I like ben’s idea of an extra address for purchases and registrations.
I have 3. One for personal and business, one for things that may give send me spam but I might check anyway, and one I use for sites that I’ll never check the email for and will probably send me copious amounts of spam.
I have 3. 1 is our main email address that we use only for friends and family. The other 2 are for everything else. We get all the spam at those 2 and our main address seldome gets any.