I've worked out a way to dynamically write numbers onto a png file!! This means I don't have to create all the png images to display as markers. It also means I can extend it to add each category to each category has a base coloured icon and I just pass in the number of the Item. It works a treat and also goes some way to remove some of the performance issues in IE6 when loading 100+ png icon files at once. I'm pleased with this one.