One word I've observed mentioned is 'gnarly', which is generally synonymous with 'cool' or 'rad'. Another one from the 50's or 60's, I believe, is 'gone'. I inadvertantly discovered an ad for a 50's or 60's recipe, and found the word there. It also means 'far out' or 'rad'.

e.g.: Gnarly, dude!
e.g.2: That pie is totally gone!