This is a very nice Authorize.net Plug-in

Very good free Authorize.net plugin to process checks and credit cards. Easiest solution to manage the merchant account to check orders, void, or refund a charge. Fantastic job by the developer! However, there are a few areas that need improvement 1.) Saving payments doesn’t work. 2.)No option for recurring payments. 3.) Payments don’t automatically change from on hold to completed after batch is captured.