Ask HN: What are some successful one-man tech companies?

In 2012 there were almost 30k "non-employer" businesses making more than $1MM / yr in revenue (see below). Some, if not many, of these must be in tech.

What are some of the most successful one-man tech companies you know?

* 26,744 had sales between $1 million and $2.49 million

* 1,723 had sales between $2.5 million and $4.99 million

*368 had sales of $5 million or more.