Work-Related:
People who abuse the "Reply All" function
People who microwave seafood or popcorn in the staff kitchen
People who talk about you like you aren't sitting in a cubicle 10-feet away
People who miss deadlines repeatedly and then demand that things be done ASAP
The woman who doesn't return e-mails for weeks at a time even though she has a freaking Blackberry. I want to push her in front of a bus.

Others:
Tailgaters
People who write checks and wait until the last minute to fill them out
People who leave clothes on the floors of fitting rooms
People who crack their knuckles and joints