If you know that one of your coworkers has a huge work load or big project to finish, offer to help. Be a team player! You could review and edit the work they've already completed or offer to take some work off their shoulders and help run reports or finish a presentation. You will be amazed how quickly the work will get done with both of you working on it!
When you offer to help a coworker you are not only helping that person, but also the company as a whole. The better quality of the work your company produces, the more honorable and respected your company will be. Not to mention you might just make a great new friend when you offer to help!
Volunteer to be the one who stays late to finish a project or take another look at tomorrow's presentation. Or offer to bring coffee early in the morning if there are people who need to get to work early to finish a report. Go out of your way to make those who are working extra hard feel extra appreciated.
Even if you are unable to help (perhaps they are in a different department that you are not familiar with or qualified for) acknowledge the hard work your coworkers have done and thank them. Let them know you appreciate their work and dedication to your office. Encourage them!