I would add the following to Pawel's answer (which is great):
Use Control Charts when looking at data - for example for Throughput and Cycle Time variation. Chart each story that finishes with the related Cycle Time it exhibited. This will show you Average, variation, add 2-Sigma control limits (easily created in Excel using trend/error lines), and you can derive possible SLA, exceptions for Kaizen moments. This is dealing with Special Cause Variation. With time, aim at improving your average.
Same can be done for Weekly Throughput - look for weeks with exceptional performance (good or bad) and think what caused it and how to create more great weeks and less bad weeks.
Buffer Management - inspired by TOC sDBR - using the Cycle Time history/SLA, when adding a card to the board, calculate when is the worst case scenario for when it should be done. now you can look at the board, and assign "colors"/"status" to cards according to the time left on their clock. e.g. if average cycle time is 7 and worst case is 14, use an SLA of 14, and start cards when you have 14 days until due date (if due date is relevant).
now, once you start, card should be green with 5-14 days remaining.
yellow with 3-6 days remaining - warning sign to start doing something about it
red with 0-3 you really need to scramble and finish this card
black - this should have been finished by now.
This provides you both with the ability to manage priorities, as well as retrospect after the fact - those reds/blacks are interesting to look at...
Another interesting area is blockers - once you find an item is blocked, mark that as a new card, with the date the blocker was created. when removed, mark the day it was removed. Then do a control chart, and also track the blocker reasons and look for trends...
There are more metrics/charts you can use - some people liked some presentations I did on the subject: