When I design websites for people, they often want to be #1 in the Google results for their category. I cannot stress enough how important INBOUND LINKS are to your online marketing efforts. The more sites that are linking to your site, the more weight sites like google will give to you as being a 'valid' site.
Get your link out there, get your affiliates and partners to link to your website, start a blog, and link to your own website like i sometimes do for Square Squared.
You can sit and think about your META tags day and night, but in the end, inbound links give you a big head start.
So now you are asking yourself, how do I know who is linking to me. Well, google offers a great way to do this. Just go to the google search box and type "link:http://www.yoursite.com" (without the quotes and no spaces) it will show you all the results of sites that are linking in to your site.
You can also use sites like www.wholinks2me.com to see Who links to my website?. And yes, I know no one is linking to this blog. Haha (the classic shoemaker syndrome).