Matt Drudge linked to this Gallup Poll which claims to show that Republicans have significantly better mental health than Democrats. Conservatives will probably have a lot of fun with this, but the poll is probably worthless because Gallup doesn't address the single biggest source of inaccuracy in any such poll: Self-reporting bias.
Unless you know that conservatives are just as likely to report mental health issues as moderates and liberals, or you understand and correct for any such bias, the data is garbage. Given the stigma still attached to mental illness among more traditional social and religious groups, members of those groups are almost certain to underreport symptoms of mental illness. For a simple but good discussion of the some of the ways surveys and studies can be biased see this web page.
To understand self-reporting bias, consider a survey asking people if they're gay. How many conservatives, particularly religious conservatives, would admit being gay to a pollster when most of them can't even admit it to themselves. Think Larry Craig and you'll understand why Gallup probably has this wrong.