Link Droppers

I’m interested in building a list of “Link Dropper” sites and would welcome
suggestions if you have any.
What do I mean by a Link Dropper? Basically a site that will drop some data into your existing webpage using a scripting language, e.g. Javascript or PHP.
My canonical example is the Meerkat Javascript Source flavour which drops RSS news feeds into your webapage. This was the first example of this kind of integration that I’d seen at the time. If you know of an earlier example then let me know.
Other examples of Link Droppers include blogrolling.com (list of blogs) and All Consuming (lists of books).
I’m interested partly because I’d like to see what kind of “annotations” I can add to this blog, but also because I’m interested in seeing what people are doing with this kind of loose integration.