Our sites use several applications and legacy systems that don't automatically crop/resize graphics and whatnot.  Ideally, the apps would take whatever they are given, convert to a nice format, crop/resize accordingly, then put them in the right place.  Some of our apps do this already, but some of the older ones don't have this ability.

We also have a lot of random users using a lot of different projects, and it is hard to keep the limits for each project straight.  Over time, more and more people involved forget the limits, so they do whatever they think looks good, and by the time several months go by, there is no more standard.  

Using imagemagick, twitter, and hpricot, I wrote a short ruby script that grabs the pages that end up getting published & checks them for consistency.  If it finds a problem, it'll send me a quick msg on twitter & log the error so we can put real eyes on the problem and get it fixed.  I tossed this into a cron job that will run every morning, so I don't have to remember to run this script all the time.

It's quick and dirty, but it gets the job done.  I'm sure there are ways to clean it up and make it more efficient, but I'm not going to worry about that right now.