I guess this site and Happy Tails (in no particular order), and then
www.spankingneeds.com.
Of course I'm leaving out a lot of great blogs with good information and pics (and I'd have to list lovingdd.blogspot.com high among those), but I chose the above due to the interactive nature of the sites.
Spankingneeds, my third choice, actually needs lots of work as it is quite slow, having only recently being despammed and moderated, but it provides a service for those interested in meetups with "theraputic spankers." (I'll leave it up to others to decide whether that is used euphamistically more often than not, but there is a consituency for disciplinary and "release" spankings separated from eroticism, and spankigneeds does seem oriented to that consitutency). Incidentally, I've met two "mentees" from there.