We have with our friends about every four months a Medieval party… and two parties ago we set up a javelin target. The javelins were of course improvised from those “arrows” you have on top of fences and broomsticks. 
My question is... what other activities one might have expected in a large "medieval" party or on sundays ? Off my head I'd say Archery and Horseshoe throwing. Any others ? Any neat ideas ?
ThanksTake your “Javelin” and a hula hoop. Have one person roll the hula hoop down the lawn, and the player has to throw the javelin through the hula hoop, stopping its forward roll. It’s a LOT harder than it sounds! Would have been done with a barrel stave back in the day, but a hula hoop works well (and is easier, because it’s bigger).
Here’s a link with more ideas. And here’s another.
Oh! You can also take your hoops (get several) and small sticks (about 8 inches long.) Using the stick and not your hands, roll the hoop down the yard. Keep whacking the back/top of the hoop with the stick to keep it rolling and upright. Now, have five people do it at once (each with their own hoop and stick) and race.
I love this stuff!
Great idea - Medieval party.
The Society for Creative Anachronism
should provide a source of all kinds of events and activities.
There are quite a few chapters around the US.
Nothing like a good joust, eh?
All you need is a mighty charger, body armor and a lance. I hear aiming for the body is the way to go, in terms of un-horsing someone… 
Bear baiting and cock fighting were all the rage back then.
Wrestling! You have your Cumberland, Box and collar… OK so those weren’t strictly medieval, but there you go.
Think of the Highland games and their assorted and bizarre collection of feats of strength.
Love those highland games where they throw logs ! I was thinking of getting some kind of very light wood… maybe even hollow it out a bit without it showing… should be great for the men to show off to the girls !
I’ll check out some of the suggestions… though SCA combat isn’t one of them !
Neat ! Should be quite hard too… since there will be only torches and candle light ! Maybe some sort of moving (with rope) target too.
You could hang a hoop and swing it while people try to throw stuff through it. Or even have someone hold it over their head and keep it moving. Really, you could have an entire evening of fun with three hula hoops and a few sticks! 
Chess and backgammon were around back then, although depending on which century you’re shooting for, the rules may be different. (With some groups, it’s good to have stuff you can do sitting down.)