You can use the Citebite tool in three different ways – there’s an extension for Firefox, there’s a bookmarklet if you are using a different browser like Chrome or IE and then you can also create deep links to pages from the Citebite website itself.
Internally, Citebite creates an exact copy of a web page, that you are linking to, on its own servers so even if the original source is down or has changed, your old citations will still work. Also, these annotated pages won’t be visible in search results as search engines are completely blocked from crawling or indexing them.