Upstart was adopted by a few distros, but then those distros left it for systemd.
Bazaar — Who uses Bazaar?
Ubuntu One — Last time I checked it supported Windows but, if you believe it, not Debian.
Ubuntu Software Centre — Debian Squeeze installs it as part of the default desktop setup. I opened it a couple of times when I first installed Squeeze and did not see anything that would make me use it, but I don’t know if it is properly integrated into Debian.
Unity — Has any distro shown interest in shipping Unity as a Gnome shell?
So, what I am wondering is: If all these extras add value to Ubuntu, why aren’t the other distros picking them up? They could add value to other distros too. And if they don’t add value to Ubuntu, why do Ubuntu and Canonical spend resources on them?