A is for Anton Karidian AKA Kodos the Executioner.
B is for the Beta Aurigae colony.
C is for Captain Christopher Pike.
D is for Deneb II.
E is for Erections caused by Jeri Ryan.
F is for those fabulous Ferengi. With their interesting modification to the transporter that removes women's clothing.
G is for Gorlan Uprising in the Mirror Universe.
H is for holograms. Starfleet or otherwise. Causing problems everywhere.
I is for Ion storms. Don't use a transporter during one.