First, I think everyone took it a bit too literally when I said "system wide setting". Maybe I phrased it wrong, but I wasn't suggesting that I flip a switch and suddenly everyone's code that's ever been written suddenly stops throwing div by zero errors. Clearly, as evidence by the many great comments in here, this would be a bad idea.
But here is my scenario. I work with an medium sized application. We have thousands of users daily. Inside the application, it displays hundreds (possibly thousands) of statistics based on data from a database. A lot of them are fairly complicated to compute and a good portion of them involve some sort of averages. We update this application very frequently and include new statistics that our customers are asking for. We're a small shop and we try to write as many unit tests as we can, but with limited # of devs and a micro budget, we can't cover as much as we'd like. New features ALWAYS take priority.
The data we receive for this application comes from about 25-30 different places and formats. Manually entered, csv files, xml files, email, faxes, etc. etc. We pretty much cater to anyone who wants to use our system and send us data, regardless of format.
Now here's the issue. Our customers use our system in very different ways. For some, a certain set of key metrics are very important to them. Others could care less about the metrics. But the point is, most of these are NOT VERY IMPORTANT. It's just fancy features we roll out to try and make our app more appealing. When one crappy little statistic happens to divide by zero and we don't trap that scenario, the whole thing takes a shit. And that sucks for user experience.
There's a very good chance that if the system is dividing by zero, it's because of the crappy data they sent us. In which case, the customer doesn't care or would understand if we told them it was off because of their data. But if they get a Div By Zero error message and can't move forward, they get really pissed.
So, all I was really saying is, in MY APP, I want to be able to set a flag that says Div By Zero just equals zero. So when my lazy programmers (including myself), forget to test a scenario for the weekly build, we don't end up spending the next day scrambling to get a hotfix out because the system is crashing for a bunch of users.
I know that doesn't fly very well here in the Slashdot crowd. And I've really enjoyed reading all the responses (even the derogatory ones). I was just frustrated and figured I probably wasn't the only one who has experienced this before. So I posted a dumb question... sue me.