I operate an RBL/ORDB-style DNS lookup service for blocking people who have sent me spam. Access is in the normal fashion; to look up A.B.C.D send a DNS "A" request for D.C.B.A.spam.pedantic.org. and you will get a result of 127.0.0.2 if and only if that address is in the listing. There is also a list of address that appear to have dynamically- or procedurally-assigned reverse DNS entries, available at netblock.pedantic.org, but it should not be used to block email. Addresses found in more popular lists at time of detection are not added to my lists.
To request removal from the spam list or exclusion from the netblock list, email firstname.lastname@example.org. If you're requesting an exclusion from the netblock.pedantic.org list, please make sure the IP address you're requesting exclusion for has a valid reverse DNS entry which doesn't appear to be dynamically assigned (i.e., doesn't have the IP address or its last octet as part of the PTR entry).
I have information about the yellow dots placed on pages by some models of color printers. This is part of the EFF effort to track down and decipher such dots.