I've worked as a CTO, in agencies, and as a one man solutions shop for small businesses. I've used 2 commercial CMSs and built 2 of my own. Very experienced developer from hardcore search algorithms to building jQuery plugins for responsive design. Just started a project to market the second CMS I wrote commercially - currently converting it to ASP.Net Core. Currently tech mentoring startups at Microsoft Ventures London.
Used to working with designers to produce professional pixel perfect front ends. Generally understand CSS better than the front end developers I've worked with. Done some interesting animation work including an scroll-animated site.
I've used SQL for a long time and am highly experienced at database schema design. There are people who understand the technical aspects better than me but I have done some quite in depth query optimisation.
I've used jQuery for years and think it's fantastic, partly from trying to write JS webapps before it was around. I've written plugins for it and hacked/fixed a few existing ones, so I know how to use it efficiently.
While I have zero Linux experience, I'm very familiar with maintaining and troubleshooting sites with decent traffic on Windows server, dealing with high cpu and memory issues, some experience of hacking attacks etc.
At my last job as CTO at a recipe publishing site, SEO was a core part of the business. I've worked with some of the best agencies in the UK, and know a lot of the most modern SEO practices, however my viewpoint is more in the publishing realm.
I think ASP.Net MVC is a fantastic platform, although I appreciate it was heavily influenced by Ruby on Rails. I've built a number of sites with it (including the largest, www.greatbritishchefs.com) and have built a CMS on it, which I'm about to launch as a commercial product, so I know it very well indeed, to the level of digging about in the open source code.
Social media were key to understand and work with from a technical point of view whether building Facebook logins, plugging in to the feed from Twitter, using the APIs and special markup and presenting sharing opportunities in the best way.