The U.S. budget would be slashed by $328 billion if certain austerity measures were put in place. Even in multi-trillion dollar budget, it is not a bad cut.
Of course, people will do nuts about the program ideas and few Washington politicians have the spine to enact such cuts, but it is a wonderful thought experiment.
Keep in mind though, that some of the cuts proposed in this piece are but a drop in the bucket of full spending. States provide a lot of funding for the mentioned programs, so it is not like they would complete dry up.
Also, note that Ireland's budget, while very small compared to the U.S. budget, is for a country of approximately 6.2 million or about the same population of Tennessee. Tennessee's budget, by the way, is $29.6 billion for FY 2010.