IT/Tech: software engineers for Obama (the Apple, Microsoft, Google, etc folks); service and support and sales likely for Romney
Just about any lower end of middle class income service occupation that probably has people a bit more educated (even if college dropouts or "taking a break") and younger than normal is going to be for Obama. My workplace was somewhere around 80-90% for Obama and broke into impromptu applause once the passage of the gay marriage bill in the State Senate was announced. 
Also call centers tend to employ a lot of minorities.
Hewlett Packard has a lot of its sales, marketing and distribution departments headquartered in Houston (along with the remnants of Compaq that was there when they got bought out). I know many people who work in the "business side" of HP as a result. Making comparisons vertically in an organization isn't always helpful because of the income effect. Of course Obama will do better in the call center than in the C-suite. But if you compare the software engineers who make an upper-middle class income to the sales and marketing people who also make an upper-middle class income, the software engineers will have more Obama voters than the marketing and sales people.
