Do people search for your keyword? Are you worried you are not getting the most out of your SEO campaign?  Part of the reason why SEO campaigns don’t work is that they could be not targeting what the customers are looking for.
Keywords could get “obsolete” in a sense that there could be newer but related keywords that are not in your web page.  Users using Google to search relevant web pages could miss your web site if they used the more recent keyword but not your keyword.
So how will you know if your keyword is still in the trend of searched keywords?  Well, Google trends from Google labs is now online for you to use, still on its early beta-stage as of this writing but still pretty usable for our purpose.
Step 1: Go to the main interface: http://www.google.com/trends
Step 2: Enter the keywords you want to study. In this case, I want to compare keywords of Drum manufacturers: Ludwig, Pearl, Sonor and Gretsch:
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Step 3: Click the Search Trends button to generate the trend chart (you should see a similar looking page like below):

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From the results above, the red line on the trend chart is the volume of Pearl Drums.  It stands out from the other known brands like Ludwig.  This verifies the common belief that Pearl is the most popular brand of drums, at least based from the number of searches from Google.
Step 4: Adjust the Region and Date Range as necessary (In this case I want all regions and the trend of the last 12 months):
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Step 5: That’s it! Use the data to your advantage.
Some of the things a web SEO might consider is to give more content for “Pearl Drums” since more readers are searching for it than the other brands.  Just by looking at the chart, Pearl Drums clearly dominate the other three keywords:
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If you are a vendor or distributor of a branded product like Pearl Drums you can sort the Regional summary by the keyword:
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After sorting it by “Pearl Drums”, Australia came up on top followed by Canada and Ireland.  If I am a SEO, marketer, or product distributor I will focus on these countries since it seems like the volume of searches  are high on these countries.
The summary by city is also helpful, since it gives information on a specific locality.  This lets local distributors focus on these cities instead of the whole country.   If your store or website targets a particular city, putting the city on the keywords of your website will help your potential customers search you easier.
Also on the Languages summary, English is followed by Finnish.  SEOs who want to grab this Finnish visitors for Pearl Drums then need to make sure that the localized Finnish translations of Pearl web pages are available.
This is only an example of what you can do with Google Trends.  You can try your own keywords, focus on shorter term date range (i.e. last few weeks), or zero in on a locale for a deeper analysis.  If you see that your keywords are going down on the volume, don’t despair, you may either up the ante on your marketing campaign or try to target the newer keywords that come up.  They key is to use the keyword trend information to your advantage.