Ah, I remember that stage well. With my daughter, when we played outside, I would encourage her to use her screaming voice. Then when we were inside, we could contrast that screaming voices are for outside and talking voices are for inside. Rather than using "no", try using positive language--use your talking voice or use your quiet voice, screaming is for outside and always model by talking in a quiet voice yourself. They're going to hear "no" so much during their young lives, so why use it when something positive will work.
We can't expect them not to scream. We just have to give them an appropriate place to do it.
Laura
Ok, I'm going to add more. I read the rest of the responses and quite a few people think time outs (and slapping!) are appropriate. For this age, I whole-heartedly disagree.
Your toddler is screaming because he can't communicate his frustration that he is not getting what he wants. I would get down on his level, and quietly say "I hear you and you're really frustrated...you are really wanting that marker...let's find a crayon and paper for "name" (basically, acknowledge his feelings and re-direct his attention). If he continues screaming, you can say "owie, that hurts mommie;s ears...screaming is for outside" and as he gets more word, you can say "use your talking". Granted, this scenario make happen a hundred times before he gets the idea, but eventually he will learn that screaming will not get him what he wants and that it's much more fun to talk with people. Also, this stage will pass as his vocabulary gets better. And then, he turns 2! LOL
Anyway, there were so many comments of consequences that have nothing to do the the behavior--time-out, slapping, I just had to put in my two sense. Natural consequences are so much more effective in the long run, and they develop an inner sense of what is right.