Can I manually re-calibrate the iPhone 4 compass?

My iPhone 4's compass is off to a significant enough degree that it's annoying... is there any way to manually re-calibrate the compass?

I have, of course, done the "figure 8" (whatever action that was supposed to elicit) when I first set up the phone, and again whenever the phone prompts me to (which is very rare). What I'm looking for is a setting/menu/option by which I can call up that re-calibration interface, instead of waiting for it to prompt me.

Update: You don't need to wait to be prompted to do the "figure eight thing". You can do it any time to recalibrate the compass.

The compass is really sensitive to outside influences. For example it is useless in my girlfriends BMW. It is consistently off by 135 degrees and doing the figure 8 doesn't make any difference. It's more of a toy than something you would want to depend on.

There is no setting in the standard iOS that allows this. The easiest way to bring that recalibration screen back up is to briefly put a magnet near your phone.

It may be better to get the real compass and not depend on smart phones. This is because all smart phones (iPhone, Samsungs, and others) all have same issue.