I really enjoy variations on the ploughman's lunch - originally cheese, bread, and some kind of relish -- both because they're delicious and because they're simple to throw together in the morning.
plain matzo, butter, homemade pickles, double gloucester
onion flatbread, goat cheese, grapefruit marmalade, olives
pugliese roll, butter, sharp cheddar, cornichons
Any combination of the above, plus a piece of fruit and some sparkling water, and you're in biz.
I think this post is kindof cool, but haven't tried the recommendations yet: http://www.chow.com/stories/11543?tag...
Personally, leftovers of dinner stuff are always my favorite for work lunch (esp. soups), but I'll also do standard sandwiches (if you want tomato bring it separately so it doesn't get soggy- I usually use cucumbers), greek yogurt with honey or with cucumbers and salt, wraps with avocado, tomato, grilled chicken, sprouts (bring a whole avocado to work and assemble there so it doesn't get brown)...
I had my first Asian sandwich recently so it inspired me to do a simple version using the new Arnold round breads. (sort of like a burger roll but not thick): sliced turkey, sliced plum tomato, sliced red onion, a little ginger sesame sauce, fresh cilantro.
For ham sandwiches just add a slice of swiss cheese and some red pepper relish with a quick 15 seconds in the microwave if available.
For afternoon snack, 4 Bistro crackers spread with roasted vegetable hummus and 12-15 grapes.