You CAN buy a house with no money down AND have no PMI. I am a realtor and have buyers on this program all the time.
The loan is called an 80/20. The loan program basically gives you two loans on your home. The primary loan, the 80% is a fixed rate mortgage for a certain period of time, say 30 years. The second mortgage, the 20%, is a variable rate Home Equity Line of Credit loan (called a HELOC) which can be paid off at any time. Say you get bonuses each year, you could sock that amount away on the 20% loan and pay it off early. Then you would be left with only the 80% loan for the remainder of your mortgage term.
Some sellers will also help with closing costs, depending upon several factors including their future plans, the home's appraisal, etc. So it is possible for you to get into a house with no money down....you just need $$ for a good faith deposit on the home.
For all this, you need fairly good credit. If you have low credit scores you can pretty much forget it.