Anyone got a nice spreadsheet of who has acquired what, with the fate of the acquired unit and people? How long did they stick around? That seems like the minimum - maybe there are clever ways to add information to it.
https://en.wikipedia.org/wiki/List_of_mergers_and_acquisitio...!
One could argue that that the last acquisition that worked out was the acquisition of Stamped. Something tells me they were behind the new Yahoo! Weather iPhone app which is stellar.
I think Yahoo's problem with acquisitions has been that they are moderately successful initially and then drift away over time. ViaWeb, GeoCities, Musicmatch Jukebox, Konfabulator, delicious and Ludicorp (of Flickr fame) come to mind. Other than Flickr, none of the others are still around, but they weren't disappointments soon after acquisition either.
Tumblr, on the other hand, has a lot of users that are fully addicted. I can see things turning out differently.