I use toplists on several of my blogs to trade traffic. I use the xclicks.net script or the ereferrer script. With xclicks you can control the listings and only add "friends". Ereferrer is the opposite: it shows all sources of traffic except ones you filter out.
por ejemplo,
with xclicks script:
http://deepthroatbj.thumblogger.com
Webmasters have to sign up and get approved or admin adds them.
with ereferrer:
http://penismaster.thumblogger.com
I allow everything to show except filter out my own preview hits from the thumblogger control panel.
Both are remote hosted scripts that generate the toplist. I haven't come across a script I can install on my own server that will allow me to create toplists across multiple blogs.