Link Overlay Icon is a shell extension for Windows Explorer to display an arrow overlay-icon for junctions and symbolically linked files or directories. This overlay icon is different than the overlay icon for shortcuts, so that it is clear what type of file you are dealing with.
At the moment only 32bit Windows is supported.
Note that when you install this, you should restart explorer.exe (Start -> Run -> type "tskill explorer" -> OK or reboot your computer).