Fun at the Fair
You can usually buy some cheap modelling balloons if you scout around a bit. Dogs are do-able for those with a little skill. There are some instructions at:
No Hands Donuts
Buy donuts with a hole in the middle (or if you are feeling evil - with jam in the middle!) and string them up. The Brownies can then try to eat a donut without using their hands. NB: This gets very messy so put something down on the floor underneath the donuts are being eaten indoors.
Steady Hand Games
I bought two games that required some kind of steady hand gesture or a bell would sound from Tesco (£3 something each). Those who completed the task without setting off the bell received a small prize.
Higher or lower: Lay playing cards in a row and turn the first one over. The player then guesses whether the next card will be higher or lower. If they are right they continue, guessing whether the next card will be higher or lower than the one just turned over. If they guess wrongly their turn is over. Those who reached the end (you can vary the length depending on how good they are) won a small prize.
Guess the number of sweets in a jar: Fill a small jar with sweets and let the Brownies guess how many sweets are in it. The closest person wins.
Guess the name of the teddy: Print off a selection of names and choose one of them as the winning name (if there are a large number of names choose a second and third as runner ups in case the original name is not chosen). The Brownies can then sign their name against the list.
Guess where the pirate treasure is hidden: Draw a pirate map onto card and then draw grids across it. Choose one of the squares to be the location of the treasure. The Brownies guess squares and the one who guesses correctly wins.
Other Side Show Games
Giant Hoopla: Arrange small prizes onto chairs and then the Brownies can try to throw hoola hoops over the chairs.
Beanbag toss: Cut holes in boxes for the Brownies to aim at. Each box can be worth a different number of points. Who can score the most?
Penny drop: Place a 20p in the bottom of a bucket of water. Brownies can drop pennies into the water. If one lands over the 20p they win it. (Different amounts can be used.)
Malteser game: Pile a small amount of flour into a heap and place a malteser on top of it. The Brownies have to pick up the malteser without using their hands. (Very messy!)
Apple bobbing: Place apples in a bowl of water. The Brownies try to eat one without using their hands. A messier version of this uses whipped cream instead of water and jelly sweets instead of apples. Think through hygiene issues before attempting.
NB: You will probably want to get permission from their parents first - be aware of any allergies.