Previously, the good folks at GPUG had a certification for AP end users. This was a great way to ensure that end users had the skills they needed to properly process payables. Now they are launching a Professional Certificate in Accounts Receivable (PCAR) providing similar knowledge and training for AR users.
I've recommended the PCAP to clients as a great resource and I'm sure that the PCAR will be fantastic as well. Follow the link to learn more.