I painted a dresser using latex paint and then I thought I would add some nice shine so I applied some oil based polyurethane and the results were not satisfactory. What kind of polyurethane can i use over latex paint?

Any waterbased poly will work. Minwax makes a finish called "Polycrylic" that you can get at your local hardware store that should work well for you're project. You will need to completely remove all traces of that oil-based poly. Did you sand it off? Wipe it off while still wet? If it is dried on now and you don't wish to remove it, I'm afraid you're stuck with it's ambering appearence. Of course, you could try to repaint over that then apply the waterbased poly. Good luck!