Actually Apple until recently didn't have a cash cow per se. When the iPod was first developed Apple was making very little money, and broadening its product base was a good strategy.

I think the main popular tech giant that seems to avoid most of the consequences of the cash cow disease is Apple. Even though they are turning a profit comparable to microsoft's, you don't see nearly as many spin-offs or research departments or other leakages. Pretty much the only things that come out of Apple are its top-of-the-line products.

While this is scary for someone who would one day like to work in an industrial reaearch lab, they certainly seem to know how to make money.

On the other hand, Apple didn't have a cash-cow before the iPod, if you regard it as their first cash-cow after Jobs' return.

And going from there to iTunes, to merging the iPod and mobile phone everyone carries around, to arriving at the iPhone and iOS, and then to expand the screen size to build the iPad doesn't represent huge deviations from their core business.

Ping might fit within what the OP describes though.