Train somebody on a certain topic that you are familiar with. Use an autoresponder to tell somebody that the decision to buy the product was a good one and that they shouldn't worry about wasting money. If you sell advertising on your web site, send a letter to an advertiser asking them what the results of their campaign were good. Ask them to send you testimonials or suggestions to make the advertising more worthwhile. Anything else you can think of.
Most web hosting companies offer free autoresponders as well.
Contact your host and ask them.