The apportionment of electoral votes is based on the congressional representation for each state, meaning that each congressional seat equals an electoral vote. Since the House of Representatives is set at 435 seats and the Senate currently has 100 members, changes in electoral votes with every 10-year census are often very minute. Therefore, the number of people per electoral vote in one state is very different than the number of people per electoral vote in another.
Below is a list of states along with their populations, number of electoral votes, and a percentage that demonstrates the relative value of a vote cast in that state compared to the national average For example, on average a state is awarded one electoral vote for every 565,166 people. However, Wyoming has three electoral votes and only 532,668 citizens (as of 2008 estimates). As a result each of Wyoming's three electoral votes corresponds to 177,556 people. These people have 3.18 times as much clout in the Electoral College as an average American, or 318% (as listed in the pdf chart, downloadable below).
2008 Population vs. Electors, State-by-State information (pdf, 60.5kb)