Here's a meta-analysis of tons of different studies that concluded: Creatine and β-hydroxy-β-methylbutyrate (HMB) were found to significantly increase net lean mass gains of 0.36 and 0.28%/wk and strength gains of 1.09 and 1.40%/wk (P < 0.05), respectively. Chromium, dehydroepiandrosterone, androstenedione, and protein did not significantly affect lean gain or strength. In conclusion, two supplements, creatine and HMB, have data supporting their use to augment lean mass and strength gains with resistance training. 

Here's a key graph from the study that make it easier to understand.

http://jap.physiology.org/content/94/2/651#sec-23

"Consumption of a recovery drink after strength training workouts did not promote greater gains in FFM compared with consumption of a carbohydrate-only drink; however, a trend toward a greater increase in FFM in the supplement group suggests the need for longer-term studies. Performance variables such as muscle strength and endurance and anaerobic performance were not improved when compared with the carbohydrate-only group."

http://www.nutritionjrnl.com/article/S0899-9007%2804%2900006-1/abstract