That is an awesome site if it does what I think it does, though it looks like it's broken right now.
I've been thinking about the pizza thing again, and I was mixing up two different things.
Dooglus did an analysis in 2012 to see how many address contained "pizza coins", there was over 1 million addresses:
https://bitcoin.stackexchange.com/questions/450/is-there-any-way-to-track-an-individual-bitcoin-or-satoshi/2900#2900Conducting taint analysis the way the OP did it (the "follow-the-coins" method) isn't the right way to do it. It's a good way for finding potential suspects, but not for finding proof. For example, see this quote from dooglus regarding the Bitcoins that were stolen from allinvain in one of the first Bitcoin hacks:
I don't mean to imply that the allinvain coins haven't been thoroughly looted. They have touched 755,796 different addresses since being stolen and are currently sitting in 109,235 different addresses, including 8 from my own personal wallet. The exact same 8 as have pizza coins in them, it turns out.