I use Living Cookbook on the PC and this app is the easiest and most flexible iPod/iPhone app that I have found, to sync my recipes. It allows you to import .mxp, .mx2 (MasterCook) and .mmf (Meal Master) files, individually or in bulk. Now that the developer has upgraded the app. to sync recipes using iTunes, it is much easier to use (although the old sync worked for me, I had to keep looking up how to do it - the new method is much easier to remember!).
This application is stable and flexible: you can create your own recipe categories, import pictures & photos to accompany the recipes, and search by recipe or by ingredient. It has a shopping basket, where you can just select a recipe and it automatically adds the right quantity of ingredients to your list. It also saves the nutrition information with my recipes, so I can see how much damage Im going to do, with that Genocide-By-Chocolate recipe ;-)
The interface could be a little more intuitive in odd places - for example, you have to enter the recipes list view to search; you cannot do this from the category view. But its not a big deal - the app. allows you to search by recipe-name or by ingredient, in a really flexible way.
Finally, Im really impressed by how responsive the developer is. I have not had to ask him questions directly, but just looking at the app. blog and comments shows how fast he responds to even minor issues. It makes me feel comfortable that my treasured recipes are safe. Ive been using this app for about 2 years now - I cant say enough good things about it. Especially if you are using Living Cookbook - the best PC recipe organizer - who dont have a mobile app. themselves.