BC Business Online just sent out an article with tips to prevent email overwhelm: check it twice a day and break tasks into smaller chunks to be more productive (click link above for the full article).
I would add: definitely turn off email notifications – if you have windows pop up to tell you an email has arrived, it is very distracting. Also, I would recommend that you subscribe to blogs by reader rather than email. I use Google Reader and I have an app called G-Whizz on my phone – I can read my email, my subscriptions, and check my Facebook and MySpace from the same place. It keeps the clutter out of my inbox, plus all of my reading is in one place and easily accessible.