I was talking on Twitter and realized that the British celebrate St. Patrick's day differently then we do in the states. I thought I'd just mention the basics for those in other countries, and I welcome hearing about your traditions no matter where you live. :)
In the states we wear green colored clothing even if we are not Irish. Sometimes people wear an inexpensive pin in the shape of a shamrock, or with a saying like "Luck of the Irish" etc. This was done more when I was younger. Usually families will gather together for corned beef and cabbage dinner with carrots and potatoes. Sometimes we drink green beer (food coloring.) We have parades (Rochester photos), Some go to bars (pubs.)
St. Patrick's Day is viewed as a holiday to spend time with family and friends eating & drinking, rather then being viewed as a religious holiday.
Chicago dyes its river green and has done so since 1961. I've never hear of this tradition until this year. President Obama is from Chicago and dyed the White House fountains green. Here is a video of it. Personally I don't care for green water.
As for me I spent a quiet evening eating a traditional corned beef, and cabbage dinner, and I was thirsty for green beer. How do/did you celebrate St. Patrick's day? Here is some history. For more information click here and here.