Put simply, I need to pass a projectID to a pop up window (component) so it can us it when adding information to a database. Anyone know how to do this or where to find an example.

Just add a public variable to your TitleWindow and set it from the component
that pops the window.

Here's a very condensed version of what you need to do...

/* MyPopUp.mxml */
<?xml version="1.0" encoding="utf-8"?>
<mx:TitleWindow xmlns:mx="http://www.adobe.com/2006/mxml">
<mx:Script>
<![CDATA[
[Bindable]
public var projectId:int;
]]>
</mx:Script>
</mx:TitleWindow>

<?xml version="1.0" encoding="utf-8"?>
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml">
<mx:Script>
<![CDATA[
import mx.managers.PopUpManager;

private var popUp:MyPopUp = new MyPopUp();

private function button_clickHandler():void
{
myPopUp.projectId = 1;

PopUpManager.addPopUp(myPopup, parent, true);
}
]]>
</mx:Script>

<mx:Button click="button_clickHandler();" />
</mx:Application>

Or you can access the data in the application using
Application.application.myDataVar.

----- components/CustomTitleWindow.as -----
package components
{
import flash.events.Event;
import flash.events.MouseEvent;

import mx.containers.TitleWindow;
import mx.controls.Button;
import mx.controls.Text;
import mx.core.Application;
import mx.events.FlexEvent;
import mx.managers.PopUpManager;

public class CustomTitleWindow extends TitleWindow{

public function CustomTitleWindow(){
super();
this.setStyle("horizontalAlign", "center");
this.addEventListener(FlexEvent.CREATION_COMPLETE,
creationCompleteHandler);
this.title = "Info was Passed from Application";
var txt:Text = new Text();
txt.setStyle("fontSize", "12");
txt.setStyle("fontWeight", "bold");
txt.width = 300;
txt.text = Application.application.info;
this.addChild(txt);
var btn:Button = new Button();
btn.label = "Close";
btn.setStyle("fontSize","12");
btn.addEventListener(MouseEvent.CLICK, closeHandler);
this.addChild(btn);
}

private function closeHandler(event:MouseEvent):void{
PopUpManager.removePopUp(this);
}

private function creationCompleteHandler(event:Event):void{
PopUpManager.centerPopUp(this);
}
}
}
----- PopupPassInfo.mxml -----
<?xml version="1.0" encoding="utf-8"?>
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml">
<mx:Script>
<![CDATA[
import components.CustomTitleWindow;
import mx.managers.PopUpManager;

public var info:String = "This is the information you will need!!!";

private function clickHandler():void{
PopUpManager.createPopUp(this, CustomTitleWindow, true);
}
]]>
</mx:Script>
<mx:Button label="Pass Text to Popup"
fontSize="12" click="clickHandler()"/>
</mx:Application>