Can anyone recommend a place where there is an abundance of street art in Hamilton?

You just missed the biggest street art festival of the year! xD
www.supercrawl.ca

but outside of that, there are regular (smaller) art crawls on james street north on the second friday of every month and I think they have exhibits up then (not 100% sure). http://www.jamesstreetnorth. ca/

if you mean graffiti, I don't know much about that. there are two new murals on the side of a building at james and rebecca I think. they're really nice, they just painted them on friday.