I miss surprisingly few of those, notebook and picasa basically. Could have missed Reader but it was replaced by the theoldreader almost overnight thanks to advices here (I wasn't a community user but a solo one so I did not miss the features that may not have been replicated).
I think the bigger issue is the features google removed or modified from some of its products; like my biggest miss is true verbatim search.
Of all the things Google has killed, I really miss Notebook. It was nimble and lightweight, while Docs is bloated and drags my old machine down (not to mention my crappy internet connection).
Around 2001, Google had a nifty toll free phone service, kind of like 411, but better. You it was an early voice recognition system that would even connect your call to the business you were trying to find. I think it was called Jupiter, but a cursory search doesn't turn up anything. I miss that too.
Google Keep is basically Notebook with a mobile-focused design. It's so odd to me that they killed that product and then made an entirely new one a few years later with the same feature set.
I think the bigger issue is the features google removed or modified from some of its products; like my biggest miss is true verbatim search.