I have to say, I'm somewhat disappointed that you can't use them on-line. I just about jumped on some cars I was eying, then read the fine print and noticed that I couldn't actually use the rebate. I've never seen a Menards store in person, and being in SE-PA, I doubt I'll be driving to the closest one in Ohio anytime soon. 
The link to the coupon information on their website says that the coupon does apply to online purchases.
http://www.menards.com/main/c-13180.htm
You just print the form and send it in with a copy of your online receipt.
I do agree though that an instant discount would be much more attractive that a mail-in rebate. That would probably attract more sales. But at least the 11% rebate applies to online purchases. So one does not need to drive to a store.
