General Information USACO: individual; participate remotely; languages include Python 3.2, C, C++, Pascal, and Java. Training website w/practice problems: http://train.usaco.org/usacogate. This is the Official website. Top scoring students can be eligible to attend an intensive summer training camp. The top four students in the US could represent their country at the International Olympiad in Informatics (IOI).
College of Charleston: teams of 3 people; happens the day before the Charleston Math Meet. They use Python 3.2. Official website: http://mathmeet.cofc.edu/index.html?pg=about#2b.
Top Coder SRM: online individual contest. There are about 3 per month. Languages include Java, C++, C, and VB.NET. Has three phases, totaling 75 minutes: coding (3 questions), challenge (breaking another's code), and system testing. Official website: http://community.topcoder.com/tc .