iLocalize caught my eye about a year ago. The first thing I did was localizing the app with the app, to get me started. Since that project that went flawlessly, iLocalize has just gained more tricks to make me productive. Yeah it costs money, but imo nothing ridiculous, and well worth it.

I never needed any of the included documentation, but while I was localizing it I found it to be well written (includes a tutorial, simple flowcharts, FAQ) and helpful.

The developer has proved himself as a responsive supporter of his product, aided by a group of beta testers and localizers that are all really into the product.