The average monthly service fee for interest-bearing Web accounts is $4.13, compared with $10.43 in the brick-and-mortar world. It should be noted it's much easier to avoid that charge too. Consumers need only $550 on average in an online interest-paying account to dodge fees. Offline banks require more than $2,200. Non-sufficient funds, or NSF, fees are also slightly lower on average among online banks -- $22.51 vs. $23.87.