I have a couple that really bother me, mine comes in the form of Pure O, so I don't real visual compulsions.
Harm OCD - This is the one that landed me in the hospital for a couple of days. I've had thoughts of becoming a serial killer, hurting my family, or completely going berserk and mass murdering. I've also had them toward myself a lot of self mutilation or taking all my bottles of pills. The biggest fear for me is snapping and losing control and following through with them.
Health OCD - Any sort of odd symptom I get I'm convinced I have some sort of fatal illness. Also ones about my mom's health and worry that she has some sort of serious illness and is going to die.
I also have health worries I have more serious illness than I've been diagnosed with.
Sexual OCD - This is by far the one that I suffer with the least often. But they are fears of raping a woman, child molestation, or taking of my pants in public.
I think this is a nice form to talk about our obsessions.