The Missouri Census Data Center has a number of custom web applications that allow users to access data and create customized outputs, typically with a choice of report format, csv file and/or SAS data set. See our Inventory/Showcase page athttp://mcdc.missouri.edu/products/ .
We have just created a new variation on our popular Estimates By Age application that lets you get data at the state or county level with a wide array of age-cohort choices combined with basic demographic categories (sex, race and Hispanic origin). We have just created a variation on this app (which is linked to at the top of the page for basic app) at http://mcdc.missouri.edu/websas/estimates_by_ageC.shtml. It lets you look at these data for the 2000 and 2010 censuses.