Skills
Cross Browser. Unfortunately, Internet Explorer (IE) is still the most used browser, and even more sad is that IE 6 is the most used version . My code works in IE6, IE7, IE8, Firefox, Safari, Chrome, Opera, and more. An important point is that I don't use special stylesheets for IE, so the code is easier to maintain and the loading is faster. 
Code quality. Structured and neat code means easy maintenance. Don't be afraid if in the future someone else has to change a colour in the CSS.
Performance. Loading scripts the proper way, optimise images, fewer HTTP requests, are some of the different techniques to load the page as faster and smoother as possible.
Marketing. It doesn't matter how nice you think your site is if users don't like it or no one can find it. SEO, AB/Split testing, Multivariable testing, keyword and conversion tracking codes, funnelling, user behaviour tracking, analytics, are important points for a site success, and I'm used to deal with them.
I am currently living in London, so I am available for in-house works as contractor in London and surroundings, or as freelance working remotely for the rest of the world (Languages: English/Spanish/Portuguese).