There is the always popular Million dollar project. The kids have to buy items worth a million dollars. This helps with subtracting across zeros and/or adding decimals.
For geometry I have the kids find geometric shapes in the environment. They can take pictures or cut them out of a magazine. I usually give them a list of 20 geometric terms.
ALSO, you could read "The Greedy Triangle" to the class and have them create their own book based on geometric shapes. At the end of "the greedy triangle" they have activities to do with younger kids. I make my students include an activity to do with a kinder kid. We set aside a day where my students will read to the kinder class.
For proportions I have the kids recreate their bedroom on a smaller scale. (example:1 foot=1 inch). They can do this in a cardboard box. They have to recreate the same things they have in their room, (bed, dresser, desk etc)
At the end of the year, you can have the kids find certain concepts you covered throughout the year in real life applications. For example, they will have to find a fraction, decimal, percent, ordinal number, etc. and present it in a creative way. I had kids create a t-shirt, or a powerpoint, or even just a poster. They can find the information in newspaper articles, magazines etc. They have to show the concept in the original format. (if it is inside a newspaper article, they have to put in the whole article.)
This is all that I can think of on the top of my head, but I will look at school and see what else I can find. Hope this helps. Let me know if you need more details.