Howard Rains sent in more new photos that we don't have yet here on the blog. One is this mural of the Old Pueblo Trolley and 4th Avenue:
It's along a parking lot for Plush on 4th Avenue. The mural is half a block south of 6th Street, between Herbert and 5th Avenue, on the south side of a wall, across from the building with the wild wraparound murals. If it has an actual address, it'd be around 450 N. Herbert.
Update (January 25, 2013): This mural is gone. The artist who was painting over it told me that Rock Martinez did the original. “The trolley is gone, and the modern street car is coming,” I said. “Right; gotta keep things fresh,” was (close to) his reply. Here's a photo showing the mural being replaced: