Our sample sizes for health surveys have been too small to do in-depth analysis on race/ethnicity and economic status. One challenge is that a significant portion of the respondent pool refuses to answer the household income question (the refusal rate can be as high as 20%). So we use education levels as a proxy.
But the Pew Internet Project and other groups do have resources to share regarding minority populations, however you want to define them.
Browse through all of the Project’s reports and presentations to see if we mention your particular research interest (older Americans, those with low access to technology, those living with disability, rural residents…)
Take a look at the chart on p. 4 in "Online Health Search 2006" (our most recent general-population report on health).
(Join the conversation about these issues on e-patients.net.)