While some people might joke about autosending emails in the middle of the night to fool their bosses into thinking they are working in the middle of the night, this can actually be used for legitimate purposes.
For instance, you might want to send an email to members of your team reminding them about a certain deadline but it might be too early to do so now. Why not autoschedule an email to be sent automatically on that date?
This feature is built-in in Outlook 2007
For other email clients or services see this
Somewhat related to scheduling emails out is to delay emails you receive such that it is resent later so you can see and deal with them again. One example is Layar. Somewhat different is Boomerang for Gmail.
Scheduling tweets, facebook status updates
I'm responsible for updating my library's Twitter account. While I use Twitterfeed to autopost tweets from other sources, I often have to manually post one-off tweets. One typical example would be a tweet about say maintenance of a web service. Typically I'm informed about this say a month in advance. A tweet at that point could and would be done, but to be more effective another tweet should be sent closer to the time or even during the maintenance period for very critical services.
Clients like Tweetdeck, or services like Hootsuite, CoTweet and other services, allows you to autoschedule tweets in advance so you don't have to remember to.
Many of these services also work with Facebook statuses. As you can link tweets to other social media accounts like facebook, you can also autoschedule those indirectly by auto-tweeting something and letting it be pushed to your facebook account.
A very special use of autoscheduling tweets in advance is when you are presenting at a conference and you want tweets to be sent at the same time. You can use some of the services above, or you can use this, which autotweets as you change slides.
Recently I asked experimenting with Bufferapp. What it does is that you fill it with tweets and it then spreads out the tweets say every hour. Why would you do this?
Basically most people tend to read tweets in spurts. So for me for example between 7-8 , I am usually using flipboard to consume tweets and this is the time where I find the most number of retweet worthy news at the same time.
But rather than spam your follower's feed with like say 10 retweets in a short period of time, you can instead store it in Bufferapp which will spread out such tweets automatically (tweet times based on what you set earlier). You could of course manually schedule tweets using tweetdeck etc, but it is too much effort since you need to set times for each tweet.
Bufferapp tweets on a schedule set by you earlier which is much easier.
Scheduling blog posts
If you're like me there are days when you feel inspired to blog a lot but there are days where you suffer from mental block. Hence it's important to spread out your blog posts.
If you are using Blogger , this feature is built-in . Wordpress.com? Ditto. Using Posterous? Blog using the post by email option, and send the email in the future using one of the methods mentioned above.
This is not so much an action, as scheduling a reminder to do something or to remind of a appointment. This is a huge topic, with many possible methods, but the easiest is to use Google calender. Why? Because it allow you to receive SMS reminders (available almost worldwide).
Scheduling anything else
Other Computer related tasks can all be scheduled using task scheduler
Don't go overboard in scheduling emails, tweets etc. I am somewhat wary of scheduling things too much in advance because circumstances might change and can be embarrassing if you forget.
E.g You autoschedule an email or tweet etc to be sent out closer to the date of the event, but a few days after doing so you have to change the event date, but you forgot about this autoscheduled email or tweet.... Some of these schedulers do have a list of scheduled events which help, but not all have that.