Lots of stories and posts about Fundrace, a tool to see if your neighbor donated to a politcal candidate in this election cycle. Fundrace uses data from the Federal Election Commission. MANY other search tools provide access to this public data and sometimes you'll find interfaces that offer different access points.
A wonderful set of databases that I've used for several years come from PoliticalMoneyLine. They offer serveral free and other fee-based search services.
On the free side, you can use this interface to search and find donations by employer name or occupation of the person making the contribution.
Btw, the answer is yes, you'll find donations made by employees at Google, Yahoo, Microsoft, and other companies.
Finally, another database (also free) allows you to search PAC (political action committee) data and find out where they've put their money.
Here's the summary page for the Yahoo Inc Political Action Committee.