MagicMouseTrails is a fun freeware app that gives you the option to add customizable flowing trails to your mouse cursor.
It includes many cool effects as well as different themes (footballs, soccer balls, stars, etc.), allowing for individual customization. The trails can be set to be very discreet to very spectacular, depending on your preference. It includes the ability to set the speed, transparency, rotation, intensity, and size/length of the trails. You have a selection of themes from which to choose.
MagicMouseTrails is meant to be a fun way to spruce up the desktop and nothing more, and with its small size, you'll never even know it's there.