All the below have those niches and have converted well for me:
<a href="http://www.nastydollars.com/?wm_refer=mbates">Nasty Dollars</a>
<a href="http://www.lightspeedcash.com/link.php?s=LSC&r=omenterp">LightSpeedCash</a>
<a href="http://www.largecash.com/?v=1&cpid=7&wid=0">LargeCash</a>
<a href="http://www.oxcash.com/?Referer=mbates">OxCash</a>