We all know that keywords are important for on-page optimization, but did you know that they can also influence file names, links, and a website's architecture? With that much importance placed on the words used, many SEO gurus believe that keyword research involves hours of endless projects to find targeted keywords and keyword phrases.
In this article on my CNET:Searchlight blog, I talk about how you don't have to block out hours of time to do keyword research, and cover some of the useful "free" tools available on the web.

Sad but true! We don’t control the search engines. All we can do is endeavor to create content that the search engines will find worthy and rank accordingly.

To rank for the most generic (yet still relevant) keyword possible, your page content needs to be focused on one (or possibly a couple, but certainly no more than three) central keyword theme. Each page of your site should "sing" its own unique "song" (keyword theme) to the search engines.

Ian McAnerin, founder of SMA-NA had this to say about keywords at the MarketingProfs Thought Leaders Summit on SEO:

There are several basic types of keywords. There are what you call your volume keywords, things like pharmacy, online pharmacy, buy pharmaceuticals. If you rank well, they will very often bring in a ton of traffic but sometimes a very low percentage of actual buyers. But that percentage, based on the amount of traffic, can be significant so you certainly don’t want to avoid that. But it is also important to point out there are other types of keywords that you can aim at too.

For example, you can aim at niche keywords, where there may be just 20 or 30 a month on each, but almost every one converting into a paying customer. If you are selling things like cars, 20 or 30 a month is a pretty big thing.

What Ian is describing here is the "long tail," a critical area for search marketers to mine. (There's a great blog entirely dedicated to the long tail.)

So, if you're only targeting a handful of keywords, you're missing the boat.