brotherhood_of_LAN - 11:41 pm on Apr 28, 2013 (gmt 0)
From their FAQ
peerblock.co.uk/faq/ - The most commonly used lists - including the P2P ("Bluetack Level1"), Advertising, Spyware, and Education lists we include as "default lists" - are authored by a group called Bluetack. So if you find that some website or company is being blocked by PeerBlock, we're not the ones to talk to about it.
Try installing it and seeing if your site is blocked, if so you must be on one of those defaut lists it uses.