Here is a simple method to use blogs to increase Google rankings/alexa ratings. I thought I should share it with you since I have rarely seen people use it and it worked very well for me.
The idea is to install WordPress or movabletype(or equivalent) on your server instead of blogging at generic sites like blogger.com, blogspot etc etc. This is not technically too difficult to do and not too expensive.
Having done that, then you create the blog as a sub domain or a subdirectory of your main site. For instance, my blog is www.opengardensblog.futuretext.com which is a sub domain of www.futuretext.com
Thus, when people link to your blog, they automatically link to your site. This has the advantage of boosting up your Google rankings and Alexa ratings for your whole site
Oddly enough, I have never seen any SEO person recommend this technique – but it works great from my experience
a) This would work only if you are a truly committed blogger and are blogging things which people want to link to. It does not work if the content on your blog is fundamentally not useful to an audience(and therefore not linkable)
b) I think subdirectories work better than sub domains from an SEO standpoint. I use sub domains because our site uses subdomainis in general. I dont want to change my whole site just for that!
c) It requires long term commitment to blogging
But it works!