I carry million dollar bill Gospel tracts around in my shirt pocket at work. I don't actively evangelize in the office, but if someone asks, I feel free to give them one. I explain that it is a Gospel tract and that they should read the back, but so far, I haven't gotten into a discussion with coworkers. I think they're afraid we might start talking about deep spiritual matters, and they're right!
I've given a few of them out today, and many people keep them at their desks. So far, I've only had one rejection. One young lady was looking questioningly at the million dollar bill tract (MDB) sticking out of my pocket, so I pulled it out and handed it to her. I said, "It's a Gospel tract, check out the back." Well, you'd have thought I'd handed her a dead rat. She made a face like she was about to throw up, shook her head and handed it back to me, gingerly by the corner, as if she was afraid some of it might accidentally get on her. She managed to say, "no thanks" and was on her way. Ok then. She'll probably avoid me in the future.
But that's the exception rather than the rule. Most people smile and say, "Cool, I can keep this? Thanks!" They take it for the novelty, but there is a good Gospel message on the back of it. I would imagine that people would look it over and check out the details when they have more time. I would.
There are different varieties of MDB's at different websites - you can check them out at Living Waters.com, Custom Tract Source.com and Evangelism Team.com.
They're by far the easiest Gospel tract to hand out, and get God's Word into people's hands. You can use them to start a one to one conversation, or just hand them out and be on your way, letting them read the Gospel for themselves.
Either way, it's a good start to following the Great Commission and witnessing to others.