S.S.
My uncle Bob says about parenting: "You gotta be smarter than the animal you're training". It sounds like your little guy is giving you a run for your money! I have to say, I am never convinced when a parent says "nothing works" because when I hear more about how they have applied their discipline techniques, I can always see room for improvement (I have worked as a family therapist). It seems like often the key to disciple is the parent must first discipline themselves and commit to following through with a technique until it works. Of course, no kid, especially a will-full one is going to roll over right away. If the child is used to getting his/her way, s/he is going to be committed to following through with whatever techniques s/he has employed in the past to see that outcome again. That is not to say that the same techniques always work for every kid.
Nobody knows your child better than you, so I'm sure you can zero in on what is truly motivating to him. Does he love trips to the park? Then you have the power to grant or withhold a trip on any given day until you see an improvement in his behavior. A parent can always control access to something the child wants - and the child is free to make a choice to follow the rules to get it or not. Or, you might try a reward system like: for every time he listens to you he gets a star and after 10 starts he gets a trip to McDonalds or something else he likes. It is the same for us in the grown up world - nobody is going to give us a paycheck if we don't do our work. Remember, one of our most important jobs as parents is to help our children learn to have mastery over their behavior. It is not enough to say, 'oh it doesn't work' and give up... pick something to try, keep it simple and make sure your son understands what you are expecting of him and then stick with it UNTIL it works... Keep the goals simple and within the child's reach - start small and build on successes. Most children do eventually get with the program if the parent communicates that there is truly no alternative.
Reading over your post again, I'd like to mention that research shows that yelling doesn't work because kids learn to tune it out and spanking doesn't work because applying punishment is one of the least effective means for changing behavior (most kids will still do the bad behavior, just when you're not looking). If you think about it, neither of these are really 'techniques' so much as reactions. Be pro-active and anticipate that bad behavior is going to occur and develop a plan for dealing with it. The best plan is one that is simple to use, easy for the child to understand, is realistic with reachable goals and is motivating for the child. Then, the key to it's success will depend on how disciplined you are in making it work.
Good luck!