Is there an up-to-date list of obsolete Japanese slang and idioms? Should there be? Would this be of value, or do you think it's best left as an automatic acquisition when studying contemporary resources?

I think it could be a totally radical happening, man. Do you grok my jive, funny face, or do I need to plug you fulla lead??

http://zokugo-dict.com/

Can find some stuff. Other than that, watch bad old movies? I know that's how I learned all the bad slang in English. THREE NINJAS

Oops, I meant, for the purpose of *avoiding* outdated slang. hehe