Cuckold doesn't have to be interracial, but quite often when you look for cuckold porn you find "normal" interracial porn. It's got something to do with the (in porn) bigger black cocks which are useful to humiliate the small cocks of the white husbands (who are often only mentioned, not shown).
To me, cuckold porn has something to do with the husband cleaning the cum afterwards.
Romanvideo has some great stuff (it's pro though):
http://www.cuckoldmenow.com/TGPs/CMN_TGP64/cmn_tgp64xxxxaff.html?aid=specialoffer&mid={CUCK}
http://www.cuckoldmenow.com/TGPs/MOVIETGPS/CMN_MGP_51/cmnmgp51xxxxaff.html?aid=specialoffer&mid={CUCK}
http://www.cuckoldmenow.com/TGPs/CMN_TGP47/cmn_tgp47xxxxaff.html?aid=specialoffer&mid={CUCK}
You might wanna check cuckoldplace.com