Gmail has provided a lot of features through labs and one important feature it lacks will be "Send Mail Later" option. This kind of feature helps me a lot to send birthday wishes to my pals. As i tend to remember their birthdays on the previous day and miserably forgets on their birthday. So i was in a hunt to get this functionality but felt bitter when knew that Gmail did not and will not come up such feature as many feel this as a unwanted feature and may be misused.
But to my rescue comes 'www.lettermelater.com" . All I need to do was that register with them with the email id from which i wish to send the mail . I need not want to login to their site every time when i want to send a mail. All i want to do is just address the mail to "firstname.lastname@example.org" with some parameters. The parameters include the recipient address and the time at which the mail has to be sent. It was super cool as i did a lot of testing by changing the parameter values. Worked perfectly well. They also have this functionality packed as a widget so that one can fit into their site/blog. Their only concern is that it is not possible to send a mail with attachment which we can expect in their future releases.