Once in a while I will give a project "bid" instead of hourly, but that is generally when the client is restrained by a low budget. Only 2-3 years into programming I am charging $28 - $35 an hour depending on what I am doing. Once I gain the experience and some more time under my belt I will increase it accordingly.
I've done some calling around the area and a good average per hour for Minnesota programmers (with experience) is $90 - $110 an hour. Can't wait to join them.
I was never a freelancer but I expect the experience would be same for negotiating for salary. Just go w/ your guts in bidding $/hr. After all, you could be competing w/ someone in India. Maybe another way of for rate is = your salary $/hr * 1.5. At least that's what I would charge if I ever go freelancing. There's just too many factors in knowing how much to charge. If your client wants it done ASAP, you'll charge $$$$$ or your work load maybe lite and may charge $. So, at the end only YOU know what to charge the best.
Thanks guys - I was more just curious to know as I generally charge $40/hour when working online, but I am going to start targeting more local businesses soon & think a $60/hour rate would be a good rate.
FTR I have almost 7 years experience in PHP/MySQL + ranging experience in other languages.