bada_bin:

There are many that are safe, but few that are effective. Why are you down on creatine? It is a proven safe supplement that actually gives good results. I’m sure you meant decrease muscle repair time…creatine aids in this by acting as an ATP buffer in muscles and keeps them well hydrated, allowing more nutrients (amino acids) to get to them and build them up. Creatine does work, it’s worked for me, you just have to really know how to use it correctly as many people are completely clueless.
Other than protein powders and creatine…there is very little out there that is reliable to any extent, without any health concerns. Multi-vitamins are good, dessicated liver can help, but other than that I have neither seen or heard of anything, and don’t bother looking because 99% of the supplement market is a scam. There are so many things sold at GNC and Vitamin World that do absolutely nothing to help build muscle, but people buy them, and some even think they work (see: placebo effect).