I'm a work out/fitness junkie, here are some exercises that I have a lot of success with that target butt, thighs, and arms. None of them require anything other than a bit of floor space:
Exercises for your core muscles are really great because they tighten up everything in the middle section rather than just your abs. These are hard to describe, but hopefully this makes sense:
1. Get in push up position, your forearms and toes are on the ground and the rest of your body should be held off the ground. I know it sounds easy, but it really works. Make sure your back remains straight (no arching up or letting it sink down). Just think about good pushup position.
2. Get on your side and lift yourself up so that only the sides of your bottom foot and the forearm of you bottom arm are on the ground and then left the rest of your body up, again keeping your body straight. Do both sides.
*Hold each position for at least 60 seconds (I usually do 3 minutes) and repeat twice*
Other good things to try:
1. Get on your hands and knees and then extend one arm and then the leg on the opposite side of your body (right arm/left leg and then left arm/right leg). Hold the position. (I think this is a yoga position...something dog...)
2. Wall sits - get into sitting position against a wall and just stay there for as long as you can. This is awesome for your butt and thighs.
3. Jumpies - basically squats except that when you get to the lowest point, you kinda hop up. One of the best workouts ever is to do 5 minutes in a row of jumpies, rest 1 minute, and repeat this 2 times...it's the hardest 18 minutes but you will see amazing results in your legs.
4. Pushups...boring, but they work for your arms and chest.
Hope these help out a bit