I use a menu plan but don't stick to it. Meaning I just plan what our week is going to look like, what we feel like having and then go from there. We might have steak planned for Tue and actually have it thurs..that type of thing.
It really does help me stick to a food budget because then I'm not "oh that looks good" or my personal favorite...i'll think of something when I first start shopping and get half the stuff..then forget about it. =)