If you go to http://www.MtgProfessor.com you will see the "wholesale" interest rates (these are not the rates you can get) available to brokers. If you see someone offering rates at or below these daily published rates then you know that you will have to pay extra "closing costs" (lender related fees) to get the promised rate.
Also if you go to http://www.AimLoan.com you can sign up for a rate quote specific to your loan (they don't do FHA, however) and you can get a daily email with the current rate quotes for various types of mortgages.
Hope this helps.
It's a lot like the average shoe size, not very specific or useful. In general terms rates are in the low 4% range for a 30 year fixed rate loan with 20% down, but there are so many variables. What is your credit score? How much do you have down? Will you be buying with a second mortgage as part of your down payment?
BankRate.com is a good source for general information about rates, but until you sit down with a Mortgage Broker and discuss your specific scenario, run credit and see what you qualify for it's hard to be specific. Don't believe every advertisement you hear or see either. They typically highlight the best available terms that not everyone will qualify for.