Too many to list.
But I have to check to make sure that my alarm clock is set every night. Four times. I have paranoia of being late.
OCD about my music and car as well. I have 23,736 songs that are all organized with the correct artist, album, and song name. I'm still working on getting all the album art.
And same with the equipment check.
i'm with you with the whole alarm clock thing. i do the exact same thing, over and over. when it comes to computer files, i always write down the total number of songs/files, etc in a folder before transferring it to my external hard drive. i have a paranoia of files just going missing for some reason lol.
i need to double check locked doors in the house by physically trying to open them...just visually seeing that they're in the locked position isn't enough.
before going up stairs for the night, i tap the refrigerator & freezer doors to make sure they're closed all the way.
when locking my car, the headlights go on and stay on for about 45 seconds...i stand there the whole 45 seconds till the lights go out