Nearby supernova candidates?

We hear so much doom and gloom about global warming, climate change, pandemics, possible asteroid impacts etc (and humanity will survive the first three anyway, and probably the fourth too), but these are small beer compared with a supernova. So, are there any supernova candidates close enough to be of alarm?

http://www.newscientist.com/article.ns?id=dn2311

One that might go off in a couple hundred million years, and might still be close enough (~150 LY) to fry us with Gamma rays.

The Bad Astronomer on the dangers of nearby supernovae

And his Discussion of Eta Carinae and Sher 25

Previous threads:

[[url=“http://boards.straightdope.com/sdmb/showthread.php?t=152685”]Regarding Betelgeuse going supernova](http://boards.straightdope.com/sdmb/showthread.php?t=260898&highlight=Betelgeuse"}How would a close supernova affect us?[/url)

Two supernova questions

(Is it overdoing it for me to be wryly amused that the Google ad for supernova threads is “Global Warming Solutions”?)