The work crush is the attraction of two co-workers (the client/vendor relationship also qualifies) but the relationship is of mutual respect and admiration. Work crushes tend to get Starbucks together, chat on the phone, IM, and eat together. They spend so much time together or their interactions are so natural and easy that many think they are actually involved. The work crush is always platonic. If it turns sexual, it is no longer a crush and has now become an affair.
Suzie and John are each other's work crush. They eat lunch together everyday.