Here's a link to a great St. Paddy's Day commercial (complements of Guinness): http://www.youtube.com/watch?v=eteWVqVPcTQ
And now, some history for ya, in case you are wondering why the Chicago River is fluorescent:
"In the United States, St. Patrick's Day would not be St. Patrick's Day unless the Chicago River is dyed green. This tradition began in 1962, when Chicago pollution-control workers used green dye to trace illegal sewage discharges in the river. The workers thought it might be a fun way to celebrate St. Patrick's Day, so they released 100 pounds of green vegetable dye into the river – enough to keep it green for a week! The idea was a hit, and continues to this day. However, only 40 pounds of dye are used today to minimize environmental damage." Source: http://www.religionfacts.com/christianity/holidays/st_patricks_day.htm
Have a great St. Paddy's Day. Wear some green, eat some corned beef and cabbage and enjoy some Guinness or Smithwick's... slainte!