Check this link out. Hope it helps.
http://knoledge.org/oak/#remedies
There are natural remedies and there are medicinal remedies; they don't cure so much as dry up the rash more quickly. There are homeopathic remedies, soaps, herbs (i know jewelweed lotion is used for poison ivy; not so sure about oak). I believe the medicinal approach is mostly steroidal cream to calm the itching. Lots of stuff out there, but all of it will take some time to work.