I use this fun page showing the days of the week. I printed it on cardstock, glued magnets at the back, and placed it on our magnetic board. An image of a cute little ladybug goes along with it.
The kids take turns to slide the magnetic ladybug to the current day of the week. It only took a few weeks before my eldest had all the days memorized, as well as their sequence.
The "Days of the Week" Bulletin Board Activity can be downloaded here.