I follow what is basically a low carb diet and bring salads to the office about 95% of the time. Usually, they contain:
Romaine or spinach
Canned chicken or tuna (or a leftover hamburger patty, sausage link, etc.)
Whatever veggies we have on hand: Cucumber, tomato, etc.
Fresh berries, if available
A few black olives, if available
Sunflower seeds, almonds or walnuts for crunch. Just a few due to the carb content.
I switch between ranch, blue cheese and poppy seed dressings, though I like Bob's olive oil and vinegar idea.
I usually eat 2 boiled eggs for breakfast, otherwise I'd have one on my salad. :)