Wow, I had no idea that website existed! I was born in 1995 and spent my childhood growing up in West Philly. I wasn't as intensely interested in skyscrapers and general development as I am today, so I wouldn't have even thought of seeking out such a website--plus, I was too occupied with playing online Flash Player games back then!
The Neighborhoods section is an interesting read. Being that I grew up in West, I never had much of a reason to travel to Fishtown, Brewerytown, and other neighborhoods back in the 2000s. It's hard for me to remember that Fishtown was a rougher neighborhood, but those pictures from 2006 showed me an angle that I'm not too familiar with. The Piazza wasn't built yet, so the northern portion of Northern Liberties must have still been rough, and South Kensington must've still been generally untouched by development. Brewerytown started to intensely revitalize right around the time I became interested in development, so I'm less surprised by that album.
The Haddington album was also great, especially the pictures of the El before reconstruction! I miss the sounds it used to make when running over that old red viaduct when my family would catch it at 52nd Street.