OSRS_Pinger.bat is a file which allows you to see the pings of the OSRS worlds. If you want to find the lowest ping worlds, type 0 when instructed to enter a "Percentage". This percentage is taken from the ping of the world and then added to the ping of the world so you can find worlds with similar ping.
An example of this is, World 301 will give you a ping of 20, so the percentage (in this case 50) is taken from 20 to give us 10, then we combine the percentage of the ping and add it to the actual ping to create 30. Then the next world we find will only show if the ping is 30 or lower. This is to stop useless clutter such as all of the worlds being shown when you only want to find the lowest available.
To get this running, save the file anywhere on your computer as "OSRS_Pinger.bat" (without the quotation marks). From there you can follow the instructions that appear once you have executed the batch file.