Run this script in the same directory as all the .jpg files you want to rename (the format will be: "photo_00001", "photo_00002", etc..). Requires you to install the Ruby framework, but that's it. If you're on a MAC with OS X, it should already be inst

renamer.rb

i = 1 
Dir.glob("./**/*.jpg").sort {|a,b| File.stat(a).atime <=> File.stat(b).atime}.each do |f| 
  new_file = "%s-%07d.jpg" % ["photo", i]
  puts "Renaming #{f.to_s} to #{new_file}"
  File.rename(f.to_s, new_file)
  i+=1 
end