I'm trying to create an email service for  a custom object that will update the status of the record to an Approved or Rejected status based on the body. I've read through the documentation and still a bit confused on how to get it set-up. Does anyone have any examples that I could work from that fits this scenario? 

I just found out the way you can implement dynamic redirect with Flows embedded in a VF page. Here is an example of the VF page and the controller which redirect the user to the detail page of a Lead created within the Flow.

VF Page:

<apex:page controller="myAutoInsuranceController" sidebar="false" showHeader="false" >
<flow:interview name="Auto_Insurance_Quote" interview="{!myAutoFlow}" finishLocation="{!nextPage}"/>
</apex:page>

Controller:

public class myAutoInsuranceController {

public Flow.Interview.Auto_Insurance_Quote myAutoFlow { get; set; }

public String getmyID() {
if (myAutoFlow==null) return '';
else return myAutoFlow.vaLeadID;
}

public PageReference getNextPage(){
PageReference p = new PageReference('/' + getmyID() );
p.setRedirect(true);
return p;
}

}