Automatic key checker?!

Would it be possible for someone to code a program that checks for vaild keys / globally banned keys?
If you could that would be great, I have about 200 keys I need to check and I need to be able to do it quick. thanks!

Darky Key Changer does that for you. I believe you just have to put them all in one text file (formatted). I also believe it has an option that allows you to change the check delay.