"Yummly" is a great app. It's not a meal planning app per se, but helpful in generating some new ideas. I've got it on my phone (android app) and on my iPad (free).
You type in the name of a dish (or ingredient) and it will give you a list of the most popular recipes (from all over the internet).
Best thing about it is that when you are looking through the list of ingredients needed for the recipe, there is a little (+) sign in front of the ingredient which lets you add it to a grocery list.
I am usually a big fan of pen and paper, but I found this app to be quite useful in coming up with some new ideas, while trying to stick to a certain budget.
Hope this helps