It's basically japanese lunch on the go traditions, but the Just Bento site in particular also has tons of ideas for westerners, and many non-japanese or barely japanese food (eg: mini-burgers). Tips, planning advice, basic principles and tons of recipes. A great deal of her recipes are also wheat-free, and more than that are cloe enough if you simply want to cut it out rather than suffer from an intolerance and must avoid gluten altogether.

I've adopted bentos for lunch years ago (I even make them for the days I work from home, so much simpler/efficient that way) It's not for everyone as it does require some planning ahead, but once you're used to it it's easy and cheap (especially if you follow her advice and build a freezer stash, often by making extras for dinner on purpose and freezing portions that become main or side components for lunch). Maki has a very practical approach to bento, not focussed on gear or crazy decoration, just well-balanced, tasty and simple lunches. We don't have much of a tradition for eating food at room temperature in North America, often it's just because as we eat mostly hot dishes, we don't know how to spice them so they're just as good at room temperature. That tends to limit us to leftovers and a few lunch options like sandwiches. Even without following bento techniques or gearing up at all etc, there are many useful lunch ideas on that site.