Unless you qualify for the graduate programme whereby Irish graduates can get a 12 month visa for the US and US graduates for here...then there's almost a zero chance.
The green card lottery opens in Autumn each year, this year's will be for Green Cards in 2012 so even if you got one you'd have a wait.
A lot like here, only certain skill sets could easily obtain a visa for the US, medical professionals more than most. Or if you worked for a company with a US branch and you could be seconded for a year.
Looked into it all a couple of years ago and even as a professional couple, we couldn't get visas. A friend in the US is an immigration lawyer and couldn't find a way for us. Short of investing $500,000 in a depressed area in the US (yes you can still buy visas!) we have to be content with holidaying there.