Organizational challenge: How to decide on Prioritization - Product Roadmap

Every stakeholder wants their product/request to be first in priority.  How do you decide?  Here's a couple examples I worked in to give you some ideas

Yahoo.com Search Marketing (Burbank) Product dept had a score card (2009 when I was there) that included,

1. revenue impact (which comparing to Google ..is NOT a good indicator.. should be "POTENTIAL future revenue lost"
2. level of effort, 
3. urgency, 
4. lowest hanging fruit, 
5. is there a workaround
6. ...etc

CitySearch.com

1. level of effort 

Small dotcom

1. Executive team intuition/decision