Easier view for User on a List field?

You could use the tooltip.  However, you can't enter line breaks manually so you will have to run a script like this in the console:

var fld=this.getField("List Box1");
var strng="";
for(var i=0;i<fld.numItems;i++)
{
strng+=fld.getItemAt(i,false)+"\r";
}
fld.userName=strng;

Why not use a drop-down field, where more items are shown when you click the arrow button in it?

If you have a lot of options, though, it will show up with a scroll-bar. There's no way around that.