Bike polo - IMHO - is one of the funnest (is that a word?) things you can do on a bike, and here in Calgary, we have 2 dedicated polo groups that play regularly during the warmer months of the year. The oldest, continuously running games are hosted by the Grassturds with those fellas playing for close to 20 years now. In the last few years, the hardcourt game has become popular too - and its my personal favorite. Hardcourt games, as the name implies, are played on a hard surface - parking lots, hockey rinks (sans ice) - they all work. The rules are slightly different between the two games with "like" contact being allowed in the hardcourt game and mallets/balls are also different between the games.
If you like riding your bike, having the occasional bevvie, and hanging out with other bikeophiles - you owe it to yourself to come and try it out this summer - you will love it!