In general I’m in favour of the right of people to own guns. I don’t own one and probably wouldn’t but in principal I’m against any kind of ban.
That said, this amusing article in the New York Times (registration required) talks about some small US towns that have made gun ownership mandatory.
The Swiss have a similar system where every man is required to own a gun and they have an admirably low crime rate – though that’s probably because they’re swiss and not because they own so many guns.
Other towns in the USA have seen much lower crime rates and the argument is easy to appreciate – criminals given the choice would rather rob a house where you might not have a gun and and such avoid areas with mandatory gun ownership laws.
While you could argue against this in many ways, one amusing consequence is that if this was a nationwide initiative, criminals would no longer have differential incentives – every house now has an equal chance of having a gun and so they ‘d choose which houses to rob using their previous criteria. The nation would be no better off than if gun ownership was randomly distributed as it is now.

I’ve not updated this in ages mainly because I’ve been travelling all over the place. In the last 5 weeks I’ve been in Japan, South Korea, Australia, the Czech Republic and spent a night at the Hilton near Stanstead airport. I’ll make sure to catch up with all the info soon.