I switched to online banking a while back, and pay most of my bills this way. One habit I got into early on was to always check the payment address of my credit card issuers before I scheduled the payment. It's probably an unnecessary precaution, since I'm positive my bank sends payment to the credit card issuers electronically.
But I once read a story about someone who send their credit card payment to the same address month after month, and one day discovered they'd been hit with a late fee because the payment address had been changed and they hadn't noticed. (I don't remember why they weren't just using the slip and envelop that come with the bill, but that's beside the moral of the story.)
I bring this up because for the first time ever, one of my credit card issuers changed the payment address this month. Like I said earlier, it probably wouldn't have mattered if I hadn't caught it, but still, I'm glad I don't have to worry about whether my payment will be timely applied.
As a side note, I only bother with this step for credit card issuers and irregular payees. I figure that with utilities and such, they'll contact me before anything really bad happens and I'll be able to sort things out quickly at that point.