I've just discovered turkey sausage. About $1.30/pound, delicous, and 19g of protien/4oz.
Tastes GREAT on a salad.
Also, like WBA said, go with spinach. WAY better for you than iceberg. If you want lettuce get the darer stuff (Romane.)
For great salad dressing also go with WBA suggestion. I like just lemon and pepper. My mom likes vinegar and lemon. They also have those new salad dressing "spritzers." Might be something to look for.
Other ways to freshen up salads:
Hard boiled eggs. Tuna. Pico de guillo. Almonds. Sunflower seeds.