Dating fellow worker
You're with them a good number of hours a day, and you tend to see them across circumstances -- both when they're succeeding and celebrating victories, and when they're having a hard time.
They "get" you in a way others don't, because they're familiar with the work (as well as the office politics).
Although you may not be in the same department, and you might not even have to interact on a daily basis, being in a relationship with a colleague means you don't really get the chance to miss each other.
This can cause the excitement of your relationship to wear off quickly.
But whenever possible, think of creative ways to stop working together -- especially if you're in different levels of the hierarchy.
Two quick anecdotes about this: a friend of mine was an intern at a law firm where she found herself attracted to her boss.When it comes to dating in the workplace, it's always best to tread lightly.