Building products/features and then killing them when they don't work is generally fine. And renaming/merging/consolidating them isn't really killing them. But…
> Sparrow was an email client for OS X and iOS. They acquired and then killed it. It was over 1 year old.
Buying then killing is sad. Acquihire I guess?
> Google Reader was a RSS/Atom feed aggregator. It was over 7 years old.
These are the ones that feel like they hurt the internet. That was seven critical years for RSS/Atom. Investing time/money in building feed aggregators/readers meant competing against the might of Google and a $0 price point.