A better solution for multiple select
asmSelect is a jQuery plugin that answers some of these issues. A progressive enhancement is applied to the select multiple that makes it much easier to use. This enhancement automatically hides the original select multiple, and instead presents a regular select showing the available options, and an HTML list showing the already-selected options. While hidden, the original select multiple is updated as the user makes changes. (via)
I haven't played around with it too much, but it looks to be promising. I definitely think it is an advantage over the multiple select option.