I think you definitely use whatever situation you are in to share the gospel.
The KJV says "be instant in season: out of season;" so you see that we are to be ready at any time. This can mean work, play, home, out on the town, etc. In these days of small print books, cell phone applications, etc. we don't have much of an excuse, but the Word should always be on you one way or another, and that can easily mean your mind. If you allow the Holy Spirit to work, those verses will be there in your mind when you need them. I speak from experience and I am sure many of you know what I speak about.
To close I'll say this. (And this is not so much for you gumby - or anyone in particular for that matter.) Just be careful. Remember that the Bible also tells us how rewarding true work is; there's no better sleep than after a good day's effort. That means you let your actions do the talking. Christians are some of the hardest working folks, and they should be. There does come a point where one can become overbearing, and sometimes actions do speak much louder than words. There's nothing wrong with an open door policy, just make sure that you're not neglecting work. One reason is that you won't stay there too long to continue to witness. The thing about Christianity is you can never convert someone. You can plant and you can water, but God gives the increase as the Apostle Paul says.
It's a beautiful thing to be there for someone, and work is a great place to do it.