txtot is an app that helps to send scheduled SMS.
Quoting from lifehacker:
Perhaps you want to text someone, but now isn’t the right time. It’s either too late, too early, you know they’re busy, or you just want to catch them at the best time to ask. Txtot schedules those messages for later so you can compose them now and still remember to send them when the time comes.
Isn’t that useful?
Just last night, I asked my mum to help me run an errand at the bank the next day. As usual, she forgot about it. It’s my fault, as I should have sent an SMS to remind her.
Yet I forgot about it..
With txtot, I could simply schedule the SMS, and avoid the problem!