well, for a Credit Card all you need is to swipe it, and enter your pin number, and the transaction is electronically done, from the buyer to the seller.
for a Debit Card, is the same as above, they're just a different type of arrangement as the Credit Card.
for Loan Documents, you're not being paid or are paying anything, you're loaning an amount, it requires signatures and some dates, amounts and loaner info...but is not a payment per se.
so, that leaves the obvious one. for Cheques you do need a signature, amount, date and person to whom it goes, and you have to write it in ink, or something non-erasable that easily.