Via Nick Bradbury, developer of FeedDemon and TopStyle, I discovered and purchased an ebook on Shareware Business Blunders, containing common mistakes made by developers who try to sell their own software. It's based on interviews with almost 40 different shareware developers, who dispense valuable, sometimes contradictory advice. One such contradiction is an argument for having a long trial period (to increase network effects) versus have a short trial (to encourage sales)--most likely depends on the product and its ability to spread virally; one developer noticed results with allowing the product to continue to function normally with a second 30-day trial period, after the first trial period has expired. It provides a lot of general insights into the business of shareware. If you are going into the shareware business, the $47 ($37 if you are an ASP member) price, it's probably worth it as a good introduction to the issues.
From one of the advice presented, I just recently joined the Association of Shareware Professionals, which, after one day of examination, seems to provide a lot of resources and information on marketing software. The membership fee is $99, so it provides a lot more value than the book. I'm in a few other software organizations, and this has the potential to be the most valuable.
As a software developer, I don't really like the term shareware, since it often associated with poor quality software. However, it seems to refer now to products that have a trial period and is downloaded online, as opposed to packaged software, which either must be shipped or purchased at retail.