Minecarts are amazing for boss battles, I killed two eyes of chutulu on expert by using my rail lines and shooting spells and stuff at him then turning around when I was out of track and stabbing him in the eye
I am pretty sure Asphalt Blocks can make you go faster in some cases, not only boosting your movement speed but making dashes from the Tabi, Master Ninja Gear and Eye of Cthulhu shields. If I remember correctly, your dash distance is quadrupled.
Edit: That being said...I wonder if the Tabi/MNG stack with the EoC Shield...?