Here's one approach: http://pastebin.com/af8N2hjE http://pastebin.com/af8N2hjE I find that for stuff like this, it's nice to have a lot of tunables that you ca

Here's one approach: http://pastebin.com/af8N2hjE http://pastebin.com/af8N2hjE I find that for stuff like this, it's nice to have a lot of tunables that you can tweak to your taste, and basic exponential (or exponential decay) functions seem to do a pretty nice job at that. I set up some default values and ran them through a few imaginary site profiles, and the scores came out pretty sane -- ~ 1.3 for a brand new, empty site with an email address, ~ 173 for a basic site that's been around for a while and has a little traffic, ~ 1875 for a popular site with content that's getting some traffic and was updated recently. If e.g. the number of days since the last update is more important to you, then just increase the value for that tunable and you'll get a larger "falling off the cliff" result for sites that haven't been updated recently. None of this is very advanced math. There's probably a cooler, more mathy way to do it. But it should do the job.