function setposition()
{
    algset = new Array('left','right','center');
    sel=document.getElementById('theselect');
    sel.style.backgroundColor='blue';
    sel.style.textAlign='center';
    sel.style.color='orange';
    for (i=0;i<sel.options.length;i++)
    {
        if (i%2 ==0)
        {
            clr='white'; bclr='green';
        }
        else
        {
            clr='navy'; bclr='orange';
        }
        sel.options[i].style.color=clr;
        sel.options[i].style.backgroundColor=bclr;
        sel.options[i].style.textAlign=algset[i%3];
    }
}

http://coboldinosaur.com/pages/Styling_Options_for_Options.html

In modern browsers select options can now be style using most css properties. Of course, IE is still behind but it does support some styling as well.  There are a lot more options on the site.

Styling select options

form, css, html5

CSS