How much should I charge for my photo / design work?

The basic formula that I keep hearing is this:

Time + Experience + Value of equipment = what you should expect to receive for your work

This meaning that the amount of time you spend on the project comes into what you charge.  The years of experience and amount of education and expertise you have accrued also impacts your rate.  The kind of and amount of equipment you use also impacts that number.

But most people just want to know what hourly rate is everyone else charging so that you know what you are competing with.  Well, that information is readily available online at the U.S. Bureau of Labor Statistics.  You can get the mean and median hourly pay, weekly pay and hours worked, and annual pay listed there nationally and by state for almost any job out there, including photographer and graphic designers.  These numbers are not what people necessarily want to be getting paid, but what people are actually being paid or at least what they are claiming on their taxes.  This information is available annually.  Oddly, more people don't know that so if you didn't, you are not alone at all.  Here's how you find your numbers:

National Data

1. Visit the National Compensation Survey at http://www.bls.gov/ncs/ 
2. Scroll down to the tab labeled NCS Publications
3. Under WAGES, click on the most recent publication (NOTE: as websites are updated, these screenshots may change)

4. Under CONTENTS, click “Print the entire bulletin”
5. DO NOT ACTUALLY PRINT.  This publication is approximately 800 pages.  Clicking this will only bring the entire publication on the screen as a .PDF so you may view it.
6. Scroll through to the job areas that interest you. 

State Data

1. Visit Wage estimates by state http://www.bls.gov/oes/current/oessrcst.htm 
2. Select your state of interest
3. Scroll down and view the average (mean) hourly/annual pay for the respective jobs in that state.

So for example, the average hourly rate for a graphic designer in California (as of May 2009) was $27.49.  Now, what I don't know is what proportion of those wages is attributed to freelance designers and what proportion are graphic designers staffed at an agency.  What the consumer pays between the two are likely to be more similar than what a designer can expect to be paid.  But regardless, this information is invaluable and every employer and employee should be aware of what these numbers are.

Hope that helps!