Didn't do anything to celebrate besides wear a Canada T-shirt and eat fried beaver tails-on-a-stick. Will someone explain to me why there is now a National Flag of Canada Day on Feb 15th? Kind of strange to celebrate a flag if you ask me. Do you get the day off in Canada?
The site does give a nice description of flag etiquette that includes items such as "don't use it as a seat cover".
Meanwhile, it's interesting to ponder why the United Kingdom doesn't have a national holiday celebrating the nation. St George's Day is only an English holiday so that's no good. Most other countries I can think of celebrate their nationhood in someway. Many of course celebrate the day they became independent of the UK. It would be a bit of stretch to celebrate the liberation of England from the Roman Empire. Again, that would only be an English celebration.
A natural choice for a holiday is to celebrate the day a country was founded. The union of the kingdom became effective 1 January 1801 but it wouldn't really work to celebrate it on New Years Day. Anyway, it's a moot point since it really isn't in the British character to wave flags and celebrate being British. Pity.