I have a lot of the same issues Star has, but possibly quite a bit stronger.
I simply can NOT be around someone crackling plastic. It just freaks me out.
I have to have the germX type wipes in my purse. I keep the packages of 10 or so wet wipes (or a ziploc with babywipes), the individual germX type handwipes, a container of the germX gel, eyeglasses wipes (they are just alcohol wipes so i clean with them if needed), AND I have a nifty little pump spray bottle of cleaner. It is about the size of a sharpie and I refill it with alcohol.
I am forever passing the hand gel to a kid, or a wipe. Or I need more than 1 or 2 and so I use the babywipes.
Public bathrooms? I have hte pump spray bottle that started life as hand sanitizer but smelled like alcohol so I refill it with alcohol. It is AWESOME for spraying toilet seats and then wiping them with toilet paper. But I also have to spray the handle on the stall AND the bar that is for the handicapped. And I don't EVER touch the door handle after I have washed my hands. Either someone else has to open the door or I have to use a paper towel. I HATE HATE HATE HATE mcdonald's bathrooms because they never have paper towels here. I end up either taking napkins IN, or using toilet paper to open the door. But the toilet paper is a last resort. I have waited for up to 5 minutes for someone to come in and open the door because I didn't bring in a napkin and they were out of toilet paper. (That is usually a sign I need to go back on prozac.)
I am a counter. Steps, chimes, bells, telephone rings,(it is one reason why the custom phone ringtones bug me - how do you count them?).
I count the number of whatever on my plate. Carrots, ratio of peas to carrots, number of pieces of chicken, whatever. It doesn't have to be an even or odd number, I just have to count them.
I think the counting is one reason I like cross stitch. All those little squares to count and reproduce with thread.
Wiz, Jess and thank you all have various counting things and tehy each had long stretches of time where food could NOT touch or be combined. I can remember making soup by serving broth, meat, veggies, rice, etc each in a separate serving dish so they could combine it however it suited them. It was actually easier than the fight over "my food touched".
I tihnk a lot mor eof the population deals with this than will admit it.
I do know that for many people SSRI type antidepressants are a big help. The maufacturers actually promote it for this, and at least for paxil it generally needs to be given at a higher dose amount to be effective for Obsessive Compulsive Disorder (OCD) issues.