This is the overgrown code for my centralized Freenet key index, (as mentioned in Time magazine!). I don't run an index myself anymore, but I keep the code here on the off chance that someone will find it useful. It can do a lot of basic stuff, like sorting keys, culling duplicates, and merging in other key indexes. It can also do some neat stuff, like presenting a searchable, hyperlinked directory of the keys.
You're pretty much on your own for setting this up and running it, but it shouldn't be too hard -- drop the contents into your CGI directory and set a couple of (all-caps) variables at the tops of the .pl files.
If you run this keyindex, FCRC can do some neat stuff, like cull keys that aren't found, and add keys that aren't already listed.