I run/work in a small shop supporting a real estate brokerage with custom software. For every new core project, I ask if the problem can be solved in java. Not because it is the best language, or the one I am most familiar with, but because it is the language that almost all the other systems are run in. Ditto for databases--projects should use mysql unless there is a very compelling reason not to. And we use one data processing tool--pentaho kettle.

Now, we've actually had some other languages 'sneak in'--perl, bash, python, javascript. But they were for closely scoped projects and, in a couple of cases, I asked for a prototype in java and the other language first.

It is hard to do this, because I read hacker news and am interested in keeping my skills up to date with the latest and greatest interesting technologies. I and my team have other alternatives to explore (hackfests, not-work side projects), which makes it easier. I'm doing the right thing for this company, and that's the right thing to do.