Postal rates have not increased since 2002, and the USPS doesn't want us to feel neglected, so they are increasing the rates as of January 8.
 
Click Here to pre-order 39cent stamps ($1 shipping fee, but worth it if you hate to stand in line!)
 
The new Rates and Fees for domestic mail are an approximate 5.4% increase.  This link takes you to the specifics, and here is an overview:

Rate

Current

Jan. 8

First-Class Mail Letter (1 oz.)

37¢

39¢

First-Class Mail Letter (2 oz.)

60¢

63¢

Postcard

23¢

24¢

Priority Mail (1 lb.) and Flat Rate Envelope

$3.85

$4.05

Priority Mail Flat Rate Box

$7.70

$8.10

Express Mail (1/2 lb.) and Flat Rate Envelope

$13.65

$14.40

Express Mail (over 1/2 lb., up to 2 lb.)

$17.85

$18.80

Fee

Current

Jan. 8

Certified Mail

$2.30

$2.40

Return Receipt (Original Signature)

$1.75

$1.85

Return Receipt (Electronic)

$1.30

$1.35

Delivery Confirmation Retail (Priority Mail)

45¢

50¢

Delivery Confirmation Retail (First-Class Mail Parcels)

55¢

60¢

Premium Forwarding Service (Weekly Fee)

$10.00

$10.40

Money Orders (Up to $500)

90¢

95¢

 
Do you ship internationally?  You haven't been left out!  International rates will enjoy a 5.4% increase, too.  The international rate increase will be in effect on January 8 also.  Click Here for the new international rates table.
 
Ready to automate your shipping?  Check out Dazzle by Endicia (especially if you ship internationally, because you can print customs form right from the shipping label).  Great report tracking and customization!
 
Stamps.com offers a free trial, scale and postage.  Check them out and see how much time you save!