What might my user have installed thats going to break my web app?
<p>There are probably thousands of applications out there like '<a href="http://radar.oreilly.com/archives/2005/05/google-web-acce-1.html" rel="nofollow">Google Web Accelerator</a>' and all kinds of <a href="http://www.google.com/tools/firefox/toolbar/FT5/intl/en/index.html" rel="nofollow">popup blockers</a>. Then theres <a href="http://stackoverflow.com/questions/257609/which-browsers-plugins-block-httpreferer-from-being-sent">header blocking</a> <a href="http://en.wikipedia.org/wiki/Personal_firewall" rel="nofollow">personal firewalls</a>, <a href="http://www.netnanny.com/" rel="nofollow">full site blockers</a>, and <a href="http://www.ccsf.edu/Info/FAQ/cookies.html" rel="nofollow">paranoid cookie monsters</a>.</p>

<p>Fortunately Web Accelerator is now defunct (I suggest you read the above article - its actually quite funny what issues it caused) but there are so many other plugins and third party apps out there that its impossible to test them all with your app until its out in the wild.</p>

<p>What I'm looking for is advice on the most important things to remember when writing a web-app (whatever technology) with respect to ensuring the user's environment isnt going to break it. Kind of like a checklist.</p>

<p>Whats the craziest thing you've experienced?</p>

<p>PS. I may have linked to net-nanny above, but I'm not trying to make a porn site</p>
