Why should the author try to fulfill some sort of gender-quota? The purpose of the article is clearly to collate the top 10 single-founder startups, rather than the top 5 male and top 5 female single-founder startups, etc.

This one comes to mind:

http://www.nastygal.com

https://www.youtube.com/watch?v=VAVq-sW6LCA

Not sure I'd call it a "tech" startup, but it definitely counts as a startup and a successful one. Apologies to #2 if I'm wrong about it being sole founder. I'd say it's more successful than some of the revenue-free entries on this list.

I believe its ranked by valuation and/or users/subscribers

This is an excellent question. There are plenty of tech companies which happen to have been founded by one woman. Why not include some? I suspect this wasn't a deliberate oversight by the author, but it does illustrate the benefit of having an editor or some other feedback before clicking Publish.

Examples:

Blurb, founded by Eileen Gittins

Mightybell, founded by Gina Bianchini

LearnVest, founded by Alexa von Tobel

Joyus, founded by Sukhinder Singh Cassidy