I had built a Chrome extension which does this.
Note: I built this for just 2 sites - just for the heck of it - by no means it's professional quality™. Please don't flame me for crappy code :)
manifest.json
{
"name": "URL Redirect",
"version": "0.1",
"description": "Checks URL and redirects as required.",
"background_page": "bg.html",
"content_scripts": [
{
"matches": ["http://*/*"],
"js": ["content.js"]
}
],
"permissions": ["tabs"]
}
bg.html
<html>
<script>
chrome.extension.onRequest.addListener(function(request, sender) {
chrome.tabs.update(sender.tab.id, {url: request.redirect});
});
</script>
</html>
content.js
var pattern=/\bIWSS/
var hnold = /news.ycombinator.com/
var imgur = /imgur.com/
var new_image = "http://sbhat.me/u/fetch_images.php?ImgUrl="
var newurl
if (pattern.test(window.document.title)) // if it matches pattern defined above
{
if (window.location.href.match(hnold)) // redirect from news.ycombinator to hackerne.ws
{
newurl = window.location.href.replace(hnold,"hackerne.ws");
}
else if (window.location.href.match(imgur))
{
newurl = new_image + window.location.href;
}
chrome.extension.sendRequest({redirect: newurl}); // send message to redirect
}
To install this, create files with filenames as mentioned above the codeblock.

Once all 3 files are created, Click on Wrench -> Tools -> Extensions. Click the "+" on Developer Mode. Click on Load Unpacked extension and point to the directory where the files are stored.

Edit the files are required, and uninstall and reinstall the extension as mentioned above