You can receive payments, but probably not donations without linking your bank. There's also a spending/sending limit of somewhere around $2000? before you have to link a bank account, or at least there used to be.
An easy way around this (at least in the US) is to sign up for PayPal's prepaid debit card. There's a $4.95 monthly fee, but you can load cash directly to it from your PayPal balance or use it for direct deposits - in fact, they recommend setting it up as a bank account in your PayPal account for 'basic' (non-instant, but also exempt from daily/monthly transfer limits) transfers. Works as a standard debit card everywhere, including ATMs; it also lets you create virtual card numbers, which can be cancelled when you're done with them, for no additional fee, in case you want to buy a flashcard off a shady Chinese site and don't want your real card info stolen or something.
Full disclosure, that's a referral link above; if you sign up through it and add $10 to the card, we each get a $5 bonus.
