if you reload get yourself some 180gr xtps from hornady (they provide good expansion and good penetration). also you need some 2400 and depending on what type of gun you have it depends on how much powder you put in there. ruger blackhawk and contender probaly work your way up to 15-16gr, slightly less in a gp-100. S&W and colts around 13-14gr.
if you havent bought anything yet though get a 44mag or a 45colt. i bought a gp-100 and now wish i would have done 2 things different, 1) bought a single action (double action is usless in hunting), 2) gone with the 44mag or 45colt
check out the paco kelly's writings on the .357 for hunting at www.sixgunner.com/backissues/default.htm you have to scroll down a little. good reading though, brought my hopes up about my .357.

if buying factory ammo, remington core-locts or if you have money to spend, winchester's supreme partion golds. stay with heavy bullets weights though for good penetration