Bondage Finder
sponsored by the ultimate BDSM website, Wasteland, here's a totally free database of BDSM personal ads! 

CollarMe.com
CollarMe is a BDSM personals site which is free to join!

Bondage.com
The original, the one and only; this site is *huge* and has both free and paid memberships available. Well worth a visit!

Alt.com
the original ALT... huge database of personals, chatrooms, and lots more!

Kinky Personals
huge database of all kinds of kinky contacts! place a free ad, or join their membership section for unlimited searching of kinky ads!

MoonKissed
totally free BDSM personals plus other BDSM resources including safety tips and more!

BDSM Cafe Personal Ads
another great site by B and Belle, more free BDSM personal ads!

Fantasy Match
searchable database of over 700,000 adult personal ads! join for free :)

Sex2Go
Huge database full of women and men seeking erotic encounters, including every type of fantasy!

Twilight Classifieds
men and women seeking alternative relationships!