No Deposit bonuses are not so common these days as they are open to abuse from players who simply want to use bonus funds and see if they can win something, whilst having no intention of depositing funds into the newly registered account.
To counter this, many online casinos, now offer a deposit match bonus whereby they will match, or even multiply the amount you deposit on your first transaction.
That said, no deposit bonus offers for casinos can still be found from time to time.