As part of Twitter's multi-part 2011 Year in Review report, the company has revealed a list of hot topics covering a variety of categories. The top hashtags, comprised of current events and Internet memes, include #egypt, #tigerblood, and #threewordstoliveby. These represent the uprising in Egypt, Charlie Sheen's catch phrase and quite simply, three words to live by.

In the technology category, the Mac App Store was the top topic followed by Sony NGP and Guitar Hero. Mozilla Firefox and Duke Nukem Forever round out the top five. In cities and countries, Cairo, Egypt and Japan were the top three topics. On par with cities and countries, the world news category was topped by Mubarak's resignation, the raid on Osama bin Laden's compound and the Japanese earthquake and the resulting Fukushima nuclear disaster.

Sports fans were busy tweeting about Wayne Rooney, Dallas, Rashard Lewis and the Texas Rangers. Those topics were tops in soccer, football, the NBA and baseball, respectively.

Charlie Sheen was the most discussed actor in 2011, which makes sense considering #tigerblood was the second most popular hashtag and Two and a Half Men ranked second in the television category behind Pretty Little Liars. Hot actresses for the year include Elizabeth Taylor, Mila Kunis and Anne Hathaway.

The top topics report is the third in a five-part series that is being released by Twitter this month. On December 1, the social networking site released a list of the top stories in 2011. The next day Twitter published a who's who list of celebrities and public figures that joined the site this year.