So I dug up my old "Quidditch Through the Ages" and this is what it says about broom sports.
There is an annual broom race in Sweden. It is a three hundred mile race that passes through a dragon reservation.
The Germans play Stitchstock. But it died out in the fourteenth century. (Modern revival perhaps?)
Aingingein was played in Ireland. It is a type of obstacle course on broomstick.
Although it is banned, Scotland once played the deadly Creaothceann.
Shuntbumps is a form of jousting on broomsticks popular in Devon, England. It is still a children's game.
Swivenhodge was also played in Herefordshire, England. Players use the end of their brooms to swish an inflated goats bladder across a hedge.
I hope this helps!
What also might be fun is to experiment with some winter sports, ones that could have originated in countries in the Artic Circle.
I was recently wanting Happy Feet with my niece (but I like it too), and while all the penguins were sliding down the icy cliff, I kept thinking to myself "there has to be a wizarding sport in this somewhere". Maybe they even hold the Olympic game in Antarctica for the sport.
I'm not quite sure how it would work myself, but it would be something fun to mull over at the very least.
Also, I very sure wizards could have at least a few water sports as well. Maybe something originally played by merpeople then revitalized to be played by wizards.
Muggle Olympics have fencing, so I'd expect the wizard equivalent to have dueling. We know that it's a competitive sport of some kind--after all, Flitwick is supposed to be a champion.