A few minutes ago I launched gre.gario.us, the first in a series of upcoming projects from my new development umbrella of sites called Semsym. This is the first new service I’ve launched in a while, and it works due to the fact that the simplest tools are often the most useful.
Basically, gre.gario.us takes any del.icio.us username and finds people who have bookmarked 2 or more of the 25 latest links the user has found. It then displays a list of “friends” in descending order of common link count. (lots more about the service on the about page.
The site uses PHP with some HTML regular expression parsing; I took great care to put most of the burden on MY servers, not del.icio.us. In fact, nearly everything (user pages and URL pages, to be exact) is cached daily; the first time a user or a URL is accessed through gre.gario.us in a day, the page will hit del.icio.us and call for the page. If it’s already been accessed – even if the URL has been used by another gre.gario.us user – it runs from the cache. That means that the friend list updates daily, so there’s some incentive to go back to the site.