In trying to design a chore system that worked for my family, I wanted something simple, flexible, and easy to customize for that particular day, while still ensuring that the necessary weekly and monthly chores were completed often enough to keep the house looking decent. I've worked on this system for my family for at least five years now, updating and refining it once or twice a year. I'm pretty happy with how it is working, although I'm still fine-tuning the individual lists of what needs to get done.
Our chart consists of two pages - one that shows each day of the week and each person's chores for that day and the other that shows a list of monthly chores. On certain days there is a spot for a monthly chore, and then I'll pick one from the monthly list, cross it off, and write it up on the picture frame. Each month I'll print out a new copy of the monthly list. This way those chores that don't need to get done every week aren't neglected and I have an easy system to make sure they get completed.
If anyone is curious, I've added our current lists below (click on the image for a larger version). These change pretty frequently (every 2-3 months, probably) as children get older and more skilled at various tasks. I also like to rotate what they do so they get experience with a variety of jobs. I should also note that everything in Nathan's column is really done by Nathan and me - I have not subbed out all the mopping to the three year old!