Yea, what all would you like to know?
What is creatine monohydrate and what does it do? The main source of energy for your muscles is ATP, and it is stored in tissue cells and is used for immediate work, like picking up an object or running 100 yards. Your muscles have roughly 4 seconds worth of stored ATP. Once this is used, creatine phosphate combines with the used ATP (which is ADP) to create more useable ATP. This gives you roughly 25-30 seconds of useable energy after the 4 seconds.
Supplementing with creatine equals more readily available sources of creatine for ADP / ATP conversion. This means you can usually lift longer and harder and usually use more weight.
A side effect is water retention, and your muscles act like a sponge with creatine and water is taken in-between themgiving you a bigger look. (credit: ryan ruff)
I also take amino acids and glutamine (which is also an amino acid, but comes in a seperate pill for me) all of which help repair your muscles after workouts, and aid in protein synthesis etc...
There are many other supplements out there... what are some specifics you would like to know?