The thing that really annoys me though isn't email address handling. It's credit card number and social security number entry fields.
For credit cards, the number of times you should have to specify which type of card you're entering is literally zero. All credit cards of the same type (e.g. Visa) begin with the same number sequence. Visa always starts with 4, so, if I type 4 as the first digit, just call it a Visa card. Do the Luhn checksum validation to make sure it's a valid number and that I probably entered it correctly, and try to run the charge. If it fails, then provide an appropriate error message.
For SSN fields, the thing that annoys me is that there are basically 2 common ways of entering the number: XXX-XX-XXXX and XXXXXXXXX. So many sites and apps only accept one of the two and will complain about the other. It's ridiculous, because the presence or absence of the dashes literally has no bearing on the validity of the number. Just let me enter it the way I want.