Written by Giles Bennett
By special request, this is by no means a definitive list - as third party modules can add their own to the templates folder upon installation - but it should be pretty comprehensive.
Account management
New account
New account confirmation key
New account confirmed
Forgot password
Remind password
Admin matters
Forgot admin password
Contact form submission
Currency update issues
Stock management
Product price alert
Product stock alert
Product cron update error
Order management
NB : With most of the below, with the correct coding it's not necessary to produce one transactional email for guest orders and one for account customer orders - the same email can be used for both.
Payment failed
New invoice
New invoice (guest)
Invoice update
Invoice update (guest)
New order
New order (guest)
Order update
Order update (guest)
New shipment
New shipment (guest)
Shipment update
Shipment update (guest)
New credit memo
New credit memo (guest)
Credit memo update
Credit memo update (guest)
Newsletter
NB : Seriously - don't use Magento's inbuilt newsletter handling. One word - Mailchimp.
Newsletter subscription confirmation
Newsletter subscription success
Newsletter unsubscription success
Sharing matters
Send product to a friend
Share wishlist with a friend