You can find numerous varieties of udon.
This page describes some of the most popular kinds you'll run into.
Kitsune Udon (fried sweet tofu)
Standard Udon
Tempura Udon
Beef Udon
Power Udon
Curry Udon
Kizami Udon
Tsukimi-Wakame Udon
Hot-pot style Udon
Egg-drop soup Udon
Kasu Udon
