While most of us have probably ridden a wide variety of coaster types, there are still plenty of other types that we've yet to conquer.
My list will probably be relatively long compared to everyone else's.
-B&M sitdown
-B&M dive
-B&M standup
-B&M launched wing (I have ridden a normal wing coaster)
-Any gigacoaster*
-Any stratacoaster*
-Vekoma SLC (probably a good thing )
-Vekoma Boomerang
-Vekoma flyer
-Intamin prefab wooden
-Gravity Group wooden
-CCI wooden*
-RMC steel hybrid
-Any Giovanola coaster
-Any S&S coaster
-Any Schwarzkopf coaster
-Any Dinn wooden*
-Arrow suspended*
-Arrow hyper*
-Intamin hyper
-Intamin Blitz*
...and many more.
* means I will likely ride one of these soon.