I've found it surprisingly easy and enjoyable to cut out meat once in awhile.
I am absolutely not a vegetarian. On the contrary, I'm a veal stock swilling, bone marrow gobbling, steak tartare munching meat-o-phile.
That said, many of the most delicious foods this world has to offer do not fall under the confines of "meat".
For what it's worth, when I cook "vegetarian", I don't cut out all meat products. I will still, for instance, fry potatoes in goose fat, or something similar.
Why the poo-pooing of the veggie stew? One of my favorite things! Make vegetarian chili, it's delicious.
Anyway, here are my favorite "meatless" items:
-Eggplant (parmesan, or grilled and topped with brown butter sauce and truffle oil, or any number of other ways. Eggplant is life)
-MUSHROOMS (mushroom ravioli, sauteed oyster shrooms, roasted maitake, mushroom terrine, chanterelle quiche, mushroom crostini, etc. Can't go wrong)
-Terrines (aforementioned mushroom, or tomato and mozz terrine, or squash, or whatever. Have fun with it)
-Soups (I like my apple & rutabaga and my celeriac & stilton. Millions of dynamite veggie soup recipes out there. Serve with warm bread)
Oftentimes, I prefer something very simple actually, simpler than any of the above. Very little compensates for a hard day at the office quite like some roasted asparagus, olive oil, and a poached egg. Simple roast cauliflower is also a big favorite of mine. In season, I eat a TON of sweet corn, just grilled, most often.
EDIT: OH, and WILTED GREENS! I eat wilted spinach or tatsoi 2-3 times per week. With the Tatsoi, I like to eat it with some shoyu, lemon, and siracha. The Spinach I do in the "catalan" style, like the tapas, with lemon, pine nuts, et cetera. Delicious and good for you!