Firefox's approach
That doesn't seem a lot better - I know what it wants me to do with an unsigned plugin prompt - review the site, verify the download hash, review the plugin source code, look for reviews of the plugin, author, site...
What I actually do is wait 5 seconds, then click "yes do it" as soon as possible. So the utility is ... well intentioned, but still ineffective.
It's true that it's less than perfectly effective, but it serves some purpose: I almost always install plugins from the Mozilla plugin site, where a rating is immediately available, and where a virused plugin would probably get removed very quickly. Under those conditions, I know that I'm fairly safe just installing it anyways.
However, a malicious site could attempt to infect my browser by installing a plugin, which is where the timer comes in handy. It could even attempt to hide the plugin dialog with lots of other useless dialogs ("Really submit thi...
This is our monthly thread for collecting these little gems and pearls of wisdom, rationality-related quotes you've seen recently, or had stored in your quotesfile for ages, and which might be handy to link to in one of our discussions.