You could make a custom icon just by making a new class in the css file something like
.icon-topcoder {
background-image: url("http://cdn5.iconfinder.com/data/icons/Symbolicons_Transportation/24/Car.png");
background-position: center center;
width: whatever maybe 16px or 32px
height: same as what you put above
}
Or you could make a custom font file