I'm still trying to work on a full home workout myself. I am NOT a trainer, so take whatever I say with a grain of salt. But, if you're new to exercise in general and low on funds so you can't really afford much equipment, a couple of easy things to start incorporating, always keeping in mind that slow use of proper form is much better than quick:
Push ups. There are lots of variations on these (wider stance, narrower stance, one-armed, whatever), but as a very basic start: put your hands right under your shoulders, keep a straight line from head to heel, bend your elbows to lower your body while keeping your shoulder blades close together. Your elbows should point up and back, not out to the sides. Lower until your elbows are around 90 degrees, then press back up, even if your stomach has not yet hit the ground.
Lunges. Again, there are options of going forward, going to the side, doing them as walking lunges, doing them with weights, etc. But, to begin, stand with your feet shoulder width apart, feet facing front, knees slightly bent. Pick up one foot and step forward with it. Keeping your torso upright, bend at the knee so that your front knee is directly above your front ankle, and lower yourself so that your back knee either just touches the ground or stays just barely above it. Return to the start, and make sure you work both legs evenly.
Squats. Stand with your feet shoulder width apart, slight bend to the knees. Keeping your knees above your ankles, sit your hips back and lower yourself downward, bending your torso forward at the hips slightly as you do so to counterbalance your weight. Keep the weight on your heels if you can, rather than on your toes. Also, as an option, do a wall squat: press your back against a wall, lower yourself until your hips and knees are both at 90 degree angles--from the side, you will look like a chair. See how long you can hold that position. Then better it. ;) even better, if you have something like a picnic bench, stand on that on one foot, and lower yourself in a squat position until the other heel just barely touches the floor, then stand back up.
Seated dips. Sit on the edge of a chair. Put your palms on the seat, right next to your butt, with your fingers over the front edge. Walk your heels out in front of you so that your knees are perfectly straight. Push down on your hands, lifting your butt off the chair, and scoot it forward so it's handing over empty space. Keeping your shoulder down and back, bend your elbows (facing straight behind you), and lower your body until your elbows are at 90 degrees, then reverse. If this becomes easy, start propping your feet on another chair. Add books to your lap if you need more weight.
Ab exercises. Few require any real equipment. Use a variety of them. Sit ups, twists, planks, side planks, reverse crunches, drawing the alphabet in the air with your heel while lying on your back, side leg lifts, keeping your heels 6 inches off the ground with your knees straight while on your back, scorpion kick backs, all of them will help you core and cost you nothing.
You can make relatively light dumbbells by filling milk/juice/laundry detergent jugs with water. If those become too light, you can make them heavier by replacing the water with flour, sugar, or sand, still on the cheap side. With these, you gain the possibility of shoulder raises, lateral raises, tricep kickbacks, and bicep curls. You can get instructions for all of these on this site easily.
If you find that using the treadmill and/or running as your sole form of cardio gets boring for you (I know it does for me), for something like $2 you can pick up a quality jump rope. You'll be amazed at what a workout jumping rope is. Staircases are an option anywhere you have access to a tall building.
The main thing I'm missing in this is a good workout for your back. If you have a bar with which you can do chin-ups/pull-ups, that will solve much of the problem. Anyone know of particularly good other back exercises which don't use much equipment?