Google competes with software and services, like MSFT used to dominate and win the PC market in the 80s and 90s. Key software services are mail, search, and maps. Also get an established product leader in Marissa Mayer.

Investing in Tesla / Space X -- because they can afford it. A future hedge if they ever want to make the "Apple Car," they could buy Tesla outright.

Investing in DNA sequencing & research (possibly new hardware)

Buying or partnering with Telco or CableCo (although possibly hard to do at global scale for BRIC, subsaharan African investment now would ensure future potential customers in region).

Buying movie, music, and/or TV content creators. They now have the cash to do this, and it would lock up the hardware market (e.g. iTunes would be more robust, and could limit digital distribution to iOS only, or at least delay for non-iOS /Mac OS products. Stream TV (see: Olympics).

Buy Comcast and get NBC Universal as well.