used to use sudacreme,and its OK, but proper chamois cream is definately the way to go.
Prevention is better than cure. Problem I've found is what is the best way to sort out the healing process if/when you do get chaffed.
Try this,as passed down to me by a very old and very rugged cyclist.
Warning this is not for the faint hearted,but it does the trick.
After (or instead of if on tour etc.) bathing ensure affected area is as dry as possible and then douse some folded toilet paper with surgical spirit and give yourself a good wipe down. It'll sting/burn like a b#st#rd (if its really bad chaffing you could even gointo shock) - apply a liberal amount of talc, either babypowder or medicated works best,this will also cool down the affected area.
Repeat morning and night until it clears, which will be quicker than other methods. The surgical spirit will also toughen the skin which has the added effect of helping prevent chaffing.
Another alternative is to use wich hazel. You can get it as a gel. Again it smarts a bit,not as much as surgical spirit,but it'll do the job.