If you use Adwords for advertising, and if you’re not using Google Conversion Optimizer, you should be.  The results may be quite surprising.
On average, campaigns adopting the Conversion Optimizer achieve a 21% increase in conversions while decreasing their CPA by 14%
How it Works:

Observes: Conversion Optimizer studies your conversion tracking data [...]

As shoemoney has brought up many times, Adsense is typically not the most efficient option to generate revenue on your website (simply follow the money and you’ll know why).  However, it is nice for people who aren’t used to internet advertising because Google allows you to setup advertising in minutes and you can generate revenue [...]

As much as people cut down on MSN Adcenter, I actually like it; for the most part.  Relative to Google, they are quite small.  But bids are much lower, conversions are decent, and you can still make a lot of money with Adcenter.  The thing I hate most is their ad disapproval system.  When an [...]

Here is my list of the top 5 Google products that I use all the time.
Google Analytics
Provides high quality stats about website traffic.  Absolutely amazing, and 100% free.
Google Adsense/Adwords
Google advertising and it is enornmous.  The program alone brought Google over $21 billion in revenue in 2008, Google main source of revenue.  And it is only [...]

Check it out here:
http://similar-images.googlelabs.com/
Google can now help you find similar images based off appearance, instead of words.

Refine your image search with visual similarity
Similar Images allows you to search for images using pictures rather than words. Click the “Similar images” link under an image to find other images that look like it. Try a search [...]

I got this email today, it should be interesting how well it works out. I’m glad they decided to give it a try:
New Targeting Options Now Available
Yahoo! has rolled out new audience targeting capabilities that can help you reach more of the audience you want at the right time, right place…and at the right [...]