IME/IMO supplements, diet, routine is going to effect everyone differently. I've tried creatine and I did gain weight, but like the others here, I found out it was mostly water weight. I could tell because I began sweating a lot more than normal, and my weight gain did not really correlate to strength gain.
Taking protein is a safe way to go IMO. Its not going to hurt your kidneys or liver, and if taken correctly it can give your muscles full benefit of recovery and gain. It is not, however, a miracle supplement. Just because you take protein, it does not mean you will 'get ripped'. You have to put in the work too.
I have also used NoXplode, or nitrous. It is supposed to give you the energy to push through a tough workout. From what I understand its a vasodilator, meaning it expands your blood vessels allowing maximum bloodflow and therefore oxygen to your muscles allowing you to achieve max fatigue. For me, this was a waste of money. It mostly made me naseaus and made me very fidgety, but some swear by it.
Gaining muscle in a short amount of time can be done, especially for those who are not frequent 'gym goers'. I put on about 10lbs of muscle in about 6 months with Whey protein and 3-4 days of hard lifting a week. For me, the hardest part was consistency. Its not always easy to get to the gym 5,4, sometimes even 3 days a week if you have a busy lifestyle. Especially if you are going for 1 1/2 - 2 hrs a crack. Just depends on how much you want it.