And another thing to note is that that money is in the form of military contracts with American companies. It is not used to pay for Israeli infrastructure or social services AFAIK beyond a separate chunk of money ~$40 million to help pay for Israel's immigration problem [2].
1. http://www.wolframalpha.com/input/?i=3+billion%24+%2F+popula...
2. http://en.wikipedia.org/wiki/File:US_aid_to_Israel.gif (note that economic aid to Israel was stopped in 2007)