Stamps.com

This is an excellent way of handling your postage and shipping needs. I've been using it for about a month and it's very slick. You can print postage on your own printer so you don't have to go to the post office to purchase stamps.

In addition, it can print shipping labels that you can just peel and stick on your mailings. If you ship priority mail, you can save the 45 cent tracking fee because they give it to you for free!