Quoting as a reminder to myself
Dealing with flat feet/collapsed arches/over pronation
This is a pretty common problem, but if you don't address it, it's quite likely for this to cause lower back and knee problems. Not to mention it completely compromising your athletic performance.
This explains it quite well, but he does talk about some advanced concepts. Understanding what's going on will make working on the various areas easier, so google or ask if you have any questions:
http://www.mobilitywod.com/2010/08/bro-your-navicular-bone-dropped.html
First step to fixing your feet is easy, just stand on your ball and abuse the tissues of the bottom of your foot. A golf ball is preferable here.
Details here:
http://www.mobilitywod.com/2011/07/episode-279365-mob-those-lower-leg-bits.html
He also mentions attacking your posterior tibialis, which is responsible for maintaining your arch.
More details here:
http://www.mobilitywod.com/2010/12/episode-115365-lower-leg-sliding.html
http://www.mobilitywod.com/2011/07/episode-293365-haiku-winner-travel-ideas-and-your-feet.html
http://www.mobilitywod.com/2011/07/episode-293365-haiku-winner-travel-ideas-and-your-feet.html
Everything mentioned is relevant. Also try hitting your anterior tibialis, which is on the outside of your shin bone.
This video explains some concepts fairly well, and I also like the exercises they're suggesting:
http://www.youtube.com/watch?v=2AwRK3js5dg
Roll the bottom of your foot every day, and attack everything else every other day for about two weeks. As the last video states, it's important to constantly try to pull your foot into an arch.
Do this every day for a couple of reps on each leg:
http://forums.overclockers.co.uk/showpost.php?p=20956254&postcount=96
...and you could try "pen penny" every other day.
Here are some newer videos from Starrett:
http://www.mobilitywod.com/2012/08/rebuilding-your-feet-with-brian-mackenzie.html
http://www.mobilitywod.com/2012/08/rebuilding-the-feet-part-2.html