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.