This is a very old topic and I don't know if wamp has had an update to the icons since then, but I was going through my computer preparing for a reformat when I realized I never uploaded my changes to the tray icons.
So, here they are, maybe they'll help someone. I only bothered with the "on" state, and I've never seen the "off" ones since.
images_on.bmp (note: some browsers will download it directly instead of displaying it).
Just replace the one in the wamp folder, given that it still looks like it did when I installed it ages ago.