I like squidoo, quite a valuable site; for everything you mention and more search engines and branding.
Squidoo And Google
First of all, Squidoo like many other social sites do pretty well at the SERPS ( search engine results page), so a 'lens' done well, i.e well researched keyword littering and interlinks (anchors and out going) can do very well in search ( this off course this is easier said than done, but can be accomplished) and its all ethical.
Squidoo And Branding
Secondly writing there and at other sites like (wikinote, script) helps to establish you as a expert in your niche, thus your 'lens' would be directing traffic to your site ( please put back links to your site, yeah people forget),so you become a destination, and you get your brand name out there.
www.squidoo.com